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Posted to user@zookeeper.apache.org by Enrico Olivelli <eo...@gmail.com> on 2018/05/08 07:09:00 UTC
Discover LEADER from JMX
Hi,
is there any way to see in JMX which is the leader of a ZooKeeper cluster?
My problem is: given access to any of the nodes of the cluster I want to
know from JMX which is the current leader.
It seems to me that this information is not available, you can know only if
the local node is Leader or Follower.
Cheers
Enrico
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Il giorno mar 8 mag 2018 alle ore 09:55 Flavio Junqueira <fp...@apache.org>
ha scritto:
> Hi Enrico,
>
> You can determine the state of a server it via 4-letter commands. Would
> that work for you?
>
Hi Flavio,
In my case I would like to have that info directly via JMX, in order to use
4-letter words I would need an additional communication channel and it can
be quite expensive (open/close connection) as I need automatic monitoring
of the status of the cluster.
From JMX I can know if the local peer is the leader, but if the local peer
is a follower I can't ask him which is the leader from its point of view.
From your answer I guess that the final answer is no.
I did not check the code, if the change is minimal (I guess the follower
knows which is the current leadger) I can work on a patch
Thank you
Enrico
>
> -Flavio
>
> > On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com> wrote:
> >
> > Hi,
> > is there any way to see in JMX which is the leader of a ZooKeeper
> cluster?
> >
> > My problem is: given access to any of the nodes of the cluster I want to
> > know from JMX which is the current leader.
> > It seems to me that this information is not available, you can know only
> if
> > the local node is Leader or Follower.
> >
> > Cheers
> > Enrico
>
>
Re: Discover LEADER from JMX
Posted by Patrick Hunt <ph...@apache.org>.
On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eo...@gmail.com>
wrote:
> Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <ph...@apache.org> ha
> scritto:
>
> > iiuc what you are interested in the information is already available. The
> > beans have a "state" attribute which indicates following vs leading.
> >
> > Try attaching a jconsole to the running servers, use the "mbeans" tab and
> > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> > attributes, you'll see the "state" attribute there.
> >
>
>
> Patrick,
> I can't find this information.
> If I log into a "follower" I get this info only for the 'current replica'
>
> Example, I have three peers, the first one is a "Follower", on JMX I have
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - QuorumAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> following
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ConfigVersion
> .....
>
>
>
> for other peers I see only
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - QuorumAddress
>
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - QuorumAddress
>
>
> so quering only this server I cannot guess which is the current leader, the
> only information I can extract is:
> - I am a follower
> - We are a cluster of three
> - Every of the three is a PARTECIPANT (no observers)
>
> in order to guess which is the leader I have to ask to all of the three
> nodes in the cluster
>
>
Yes.
Patrick
> Am I missing something ? I am running 3.5.3-BETA
>
> Enrico
>
>
>
>
>
>
>
>
>
>
>
>
>
> >
> > Patrick
> >
> > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com>
> > wrote:
> >
> > > Thank you Edward
> > >
> > > I will pack all together and send out a patch as soon as I have time.
> > > I am running 3.5 in production and given than an RC for 3.5.4 is going
> to
> > > be cut soon I will have to wait for 3.5.5 and I assume it won't be
> > > immediate.
> > >
> > > Cheers
> > > Enrico
> > >
> > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > edward.ribeiro@gmail.com> ha scritto:
> > >
> > > > Sent before finishing the previous email. Only to complement, the
> > > > findLeader() could have been as below, but this change is only a
> nitty
> > > > detail and totally irrelevant to the questions you are asking. :)
> > > >
> > > > /**
> > > > * Returns the address of the node we think is the leader.
> > > > */
> > > > protected QuorumServer findLeader() {
> > > >
> > > > // Find the leader by id
> > > > long currentLeader = self.getCurrentVote().getId();
> > > >
> > > > QuorumServer leaderServer = self.getView().get(currentLeader);
> > > >
> > > > if (leaderServer == null) {
> > > > LOG.warn("Couldn't find the leader with id = {}",
> > currentLeader);
> > > > }
> > > > return leaderServer;
> > > > }
> > > >
> > > > Edward
> > > >
> > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > edward.ribeiro@gmail.com
> > > >
> > > > wrote:
> > > >
> > > > > Hi Enrico,
> > > > >
> > > > > Well, I am not an expert on QuorumPeer either (not an expert on
> > > anything,
> > > > > really), but maybe it's the variable and method below?
> > > > >
> > > > > ----------------- QuorumPeer ------------------
> > > > >
> > > > > /**
> > > > > * This is who I think the leader currently is.
> > > > > */
> > > > > volatile private Vote currentVote;
> > > > >
> > > > > public synchronized Vote getCurrentVote(){
> > > > > return currentVote;
> > > > > }
> > > > >
> > > > > ---------------------------------------
> > > > >
> > > > >
> > > > > Then it's a matter of calling quorumPeer.getCurrentVote().getId()
> and
> > > > > quorumPeer.getServerState()?
> > > > >
> > > > > Btw, the Learner class has this handy method below (self is a
> > > > QuorumPeer):
> > > > >
> > > > > ---------------- Learner --------------------
> > > > >
> > > > > /**
> > > > > * Returns the address of the node we think is the leader.
> > > > > */
> > > > > protected QuorumServer findLeader() {
> > > > > QuorumServer leaderServer = null;
> > > > > // Find the leader by id
> > > > > Vote current = self.getCurrentVote();
> > > > > for (QuorumServer s : self.getView().values()) {
> > > > > if (s.id == current.getId()) {
> > > > > leaderServer = s;
> > > > > break;
> > > > > }
> > > > > }
> > > > > if (leaderServer == null) {
> > > > > LOG.warn("Couldn't find the leader with id = "
> > > > > + current.getId());
> > > > > }
> > > > > return leaderServer;
> > > > > }
> > > > >
> > > > > ---------------------------------------
> > > > >
> > > > > By the way, as a side note, the map traversal could be changed by:
> > > > >
> > > > > ----------------------------
> > > > >
> > > > > if (self.getView().contains(current.getId()) {
> > > > >
> > > > > }
> > > > >
> > > > > ---------------------------
> > > > >
> > > > >
> > > > >
> > > > > You can see above this method the quorumPeer.getView() returns a
> > > Map<sid,
> > > > > QuorumServer> as below:
> > > > >
> > > > > -------------QuorumPeer ---------
> > > > >
> > > > > /**
> > > > > * A 'view' is a node's current opinion of the membership of the
> > entire
> > > > > * ensemble.
> > > > > */
> > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > > return Collections.unmodifiableMap(getQuorumVerifier().
> > > > > getAllMembers());
> > > > > }
> > > > >
> > > > > -----------------------------
> > > > >
> > > > >
> > > > > And then it retrieves the QuorumServer that has many more
> information
> > > > > about the node besides the sid (InetSocketAddress, hostname, etc).
> :)
> > > > >
> > > > >
> > > > > Cheers,
> > > > > Edward
> > > > >
> > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> eolivelli@gmail.com
> > >
> > > > > wrote:
> > > > >
> > > > >> So I am trying to create a patch in order to expose on JMX the id
> of
> > > the
> > > > >> current "leader" (on the JVM of a follower)
> > > > >>
> > > > >> I am trying to find in ZK which is the variable which holds the ID
> > of
> > > > the
> > > > >> current leader.
> > > > >> I am new to the internal of QuorumPeer
> > > > >>
> > > > >> Can someone give me some hint ?
> > > > >>
> > > > >> Enrico
> > > > >>
> > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > >>
> > > > >> > Hi,
> > > > >> > That is possible with 4 letter commands. We are using it now. In
> > > 3.5.x
> > > > >> it
> > > > >> > is going to be removed in favour of admin server (embedded web
> > > > server).
> > > > >> > We are running in an environment where it’s not possible to run
> > JMX
> > > or
> > > > >> > embedded web servers.
> > > > >> >
> > > > >> > So I am wondering if there is another way? It would be nice to
> > have
> > > > this
> > > > >> > info as a znode.
> > > > >> >
> > > > >> > Best regards,
> > > > >> > Ansel
> > > > >> >
> > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org>
> > wrote:
> > > > >> > >
> > > > >> > > Hi Enrico,
> > > > >> > >
> > > > >> > > You can determine the state of a server it via 4-letter
> > commands.
> > > > >> Would
> > > > >> > that work for you?
> > > > >> > >
> > > > >> > > -Flavio
> > > > >> > >
> > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> eolivelli@gmail.com>
> > > > >> wrote:
> > > > >> > >>
> > > > >> > >> Hi,
> > > > >> > >> is there any way to see in JMX which is the leader of a
> > ZooKeeper
> > > > >> > cluster?
> > > > >> > >>
> > > > >> > >> My problem is: given access to any of the nodes of the
> cluster
> > I
> > > > >> want to
> > > > >> > >> know from JMX which is the current leader.
> > > > >> > >> It seems to me that this information is not available, you
> can
> > > know
> > > > >> > only if
> > > > >> > >> the local node is Leader or Follower.
> > > > >> > >>
> > > > >> > >> Cheers
> > > > >> > >> Enrico
> > > > >> > >
> > > > >> >
> > > > >> >
> > > > >>
> > > > >
> > > > >
> > > >
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
FYI the patch has been merged to master e to 3.5 branch
thank you !
https://issues.apache.org/jira/browse/ZOOKEEPER-3066
Enrico
Il giorno gio 21 giu 2018 alle ore 17:38 Enrico Olivelli <
eolivelli@gmail.com> ha scritto:
>
>
> Il gio 21 giu 2018, 17:13 Andor Molnar <an...@cloudera.com.invalid> ha
> scritto:
>
>> Okay, let's put it this way: what kind of test would you like to add here?
>>
>> *Unit test*
>> This is a requirement for the patch to be committed. You don't need to
>> fire
>> up a full blown ensemble to test the new functionality. Pick the class
>> that
>> you'd like to test, mock out the dependencies with moquito and write some
>> quick unit tests. Your tests should finish in a few hundreds millisecs
>> (1-2
>> secs maximum).
>>
>
> This is achieved in my patch. There was already a test about JMX and
> LocalPeerMXBean. I have enhanced it, by extending the test to cover my new
> JMX attribute and, to cover even RemotePeerMXBean, which was not tested at
> all.
>
> One review comment asked me to perform assertions after a leadership
> change.
>
> I did not touch ZK internals with this patch, I am only publishing
> internal state to JMX endpoint.
>
> Maybe what I am trying to do is not needed for the patch to be
> 'acceptable'.
>
> I think it would be useful to add such test case, but not strictly needed.
> Unfortunately current test utilities seem to able to do what requested.
>
> I am able to add mockito based tests if requested.
>
>
>
>
>
>> *Integration test*
>> This is not required, but more than welcome. Can you do it with reasonable
>> amount of effort? Is it going to finish in an acceptable time frame (5-10
>> secs)? If yes, go ahead, if not, skip that.
>>
>
> Not needed. Maybe existing test case is already similar to an integration
> test ( it brings up a cluster of 5 nodes).
>
> Anyway my changes is not slowing down the full suite add I am only adding
> an assertion to an existing old test.
>
> I think the restart of the cluster it is not strictly needed and it will
> may add a new flaky test.
>
> Treating ZK as one of my projects, I think the existing JMX test corpus
> should be refactored but given the little impact of this patch is it not
> worth to spend much time.
>
>
>
> Enrico
>
>
>
>
>
>> Hope that helps.
>>
>> Regards,
>> Andor
>>
>>
>>
>>
>>
>>
>> On Thu, Jun 21, 2018 at 2:39 PM, Enrico Olivelli <eo...@gmail.com>
>> wrote:
>>
>> > Andor,
>> >
>> > I had already tried that way but without success.
>> > I have updated the patch with a proposal.
>> > Thanks
>> >
>> > Enrico
>> >
>> > Il gio 21 giu 2018, 13:20 Andor Molnar <an...@cloudera.com.invalid> ha
>> > scritto:
>> >
>> > > Hi Enrico!
>> > >
>> > > Take a look at testElectionFraud(), it might be useful to you.
>> > >
>> > > Regards,
>> > > Andor
>> > >
>> > >
>> > >
>> > > On Thu, Jun 21, 2018 at 12:00 PM, Enrico Olivelli <
>> eolivelli@gmail.com>
>> > > wrote:
>> > >
>> > > > Norbert,
>> > > > thank you for taking a look
>> > > >
>> > > > Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
>> > > > <nk...@cloudera.com.invalid> ha scritto:
>> > > >
>> > > > > Good question. Wouldn't just killing the leader do the job?
>> > > > >
>> > > >
>> > > > It seems to me that is it not "immediate" to "kill" a QuorumPeer
>> inside
>> > > > such test.
>> > > > If you "shutdown" it you cannot 'start' it anymore.
>> > > >
>> > > > This is why I am asking for help.
>> > > >
>> > > > -- Enrico
>> > > >
>> > > >
>> > > >
>> > > > >
>> > > > > Regards,
>> > > > > Norbert
>> > > > >
>> > > > > On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <
>> eolivelli@gmail.com
>> > >
>> > > > > wrote:
>> > > > >
>> > > > > > This is my patch
>> > > > > > https://github.com/apache/zookeeper/pull/546
>> > > > > >
>> > > > > > One question:
>> > > > > > I would like to force the cluster to change leader in
>> > > > > > HierarchicalQuorumTest, so that I can test that JMX will reflect
>> > the
>> > > > new
>> > > > > > status of the group.
>> > > > > > Any idea about how to bounce the leader ?
>> > > > > >
>> > > > > > Cheers
>> > > > > > Enrico
>> > > > > >
>> > > > > > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
>> > > > > > eolivelli@gmail.com> ha scritto:
>> > > > > >
>> > > > > > > This is my JIRA
>> > > > > > > I am going to work on a patch
>> > > > > > >
>> > > > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
>> > > > > > >
>> > > > > > > Enrico
>> > > > > > >
>> > > > > > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com>
>> ha
>> > > > > scritto:
>> > > > > > >
>> > > > > > >> "in order to guess which is the leader I have to ask to all
>> of
>> > the
>> > > > > three
>> > > > > > >> nodes in the cluster"
>> > > > > > >>
>> > > > > > >> That's correct.
>> > > > > > >>
>> > > > > > >> Regards,
>> > > > > > >> Andor
>> > > > > > >>
>> > > > > > >>
>> > > > > > >>
>> > > > > > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <
>> > > > eolivelli@gmail.com
>> > > > > >
>> > > > > > >> wrote:
>> > > > > > >>
>> > > > > > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
>> > > > > > phunt@apache.org>
>> > > > > > >> ha
>> > > > > > >> > scritto:
>> > > > > > >> >
>> > > > > > >> > > iiuc what you are interested in the information is
>> already
>> > > > > > available.
>> > > > > > >> The
>> > > > > > >> > > beans have a "state" attribute which indicates following
>> vs
>> > > > > leading.
>> > > > > > >> > >
>> > > > > > >> > > Try attaching a jconsole to the running servers, use the
>> > > > "mbeans"
>> > > > > > tab
>> > > > > > >> and
>> > > > > > >> > > open org.apache.ZooKeeperService -> replicatedserver ->
>> > > replica
>> > > > ->
>> > > > > > >> > > attributes, you'll see the "state" attribute there.
>> > > > > > >> > >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> > Patrick,
>> > > > > > >> > I can't find this information.
>> > > > > > >> > If I log into a "follower" I get this info only for the
>> > 'current
>> > > > > > >> replica'
>> > > > > > >> >
>> > > > > > >> > Example, I have three peers, the first one is a
>> "Follower",
>> > on
>> > > > JMX
>> > > > > I
>> > > > > > >> have
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > > > > ClientAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > > > > >> ElectionAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > > > LearnerType
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > Name
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > > > > QuorumAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > State =
>> > > > > > >> > following
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> > > > > > ConfigVersion
>> > > > > > >> > .....
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> > for other peers I see only
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> > > > > > ClientAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> > > > > > >> ElectionAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> > > > > LearnerType
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> > Name
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> > > > > > QuorumAddress
>> > > > > > >> >
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> > > > > > ClientAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> > > > > > >> ElectionAddress
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> > > > > LearnerType
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> > Name
>> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> > > > > > QuorumAddress
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> > so quering only this server I cannot guess which is the
>> > current
>> > > > > > leader,
>> > > > > > >> the
>> > > > > > >> > only information I can extract is:
>> > > > > > >> > - I am a follower
>> > > > > > >> > - We are a cluster of three
>> > > > > > >> > - Every of the three is a PARTECIPANT (no observers)
>> > > > > > >> >
>> > > > > > >> > in order to guess which is the leader I have to ask to all
>> of
>> > > the
>> > > > > > three
>> > > > > > >> > nodes in the cluster
>> > > > > > >> >
>> > > > > > >> > Am I missing something ? I am running 3.5.3-BETA
>> > > > > > >> >
>> > > > > > >> > Enrico
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> >
>> > > > > > >> > >
>> > > > > > >> > > Patrick
>> > > > > > >> > >
>> > > > > > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
>> > > > > > eolivelli@gmail.com>
>> > > > > > >> > > wrote:
>> > > > > > >> > >
>> > > > > > >> > > > Thank you Edward
>> > > > > > >> > > >
>> > > > > > >> > > > I will pack all together and send out a patch as soon
>> as I
>> > > > have
>> > > > > > >> time.
>> > > > > > >> > > > I am running 3.5 in production and given than an RC for
>> > > 3.5.4
>> > > > is
>> > > > > > >> going
>> > > > > > >> > to
>> > > > > > >> > > > be cut soon I will have to wait for 3.5.5 and I assume
>> it
>> > > > won't
>> > > > > be
>> > > > > > >> > > > immediate.
>> > > > > > >> > > >
>> > > > > > >> > > > Cheers
>> > > > > > >> > > > Enrico
>> > > > > > >> > > >
>> > > > > > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro
>> <
>> > > > > > >> > > > edward.ribeiro@gmail.com> ha scritto:
>> > > > > > >> > > >
>> > > > > > >> > > > > Sent before finishing the previous email. Only to
>> > > > complement,
>> > > > > > the
>> > > > > > >> > > > > findLeader() could have been as below, but this
>> change
>> > is
>> > > > > only a
>> > > > > > >> > nitty
>> > > > > > >> > > > > detail and totally irrelevant to the questions you
>> are
>> > > > asking.
>> > > > > > :)
>> > > > > > >> > > > >
>> > > > > > >> > > > > /**
>> > > > > > >> > > > > * Returns the address of the node we think is the
>> > leader.
>> > > > > > >> > > > > */
>> > > > > > >> > > > > protected QuorumServer findLeader() {
>> > > > > > >> > > > >
>> > > > > > >> > > > > // Find the leader by id
>> > > > > > >> > > > > long currentLeader =
>> self.getCurrentVote().getId();
>> > > > > > >> > > > >
>> > > > > > >> > > > > QuorumServer leaderServer =
>> > > > > > self.getView().get(currentLeader);
>> > > > > > >> > > > >
>> > > > > > >> > > > > if (leaderServer == null) {
>> > > > > > >> > > > > LOG.warn("Couldn't find the leader with id =
>> > {}",
>> > > > > > >> > > currentLeader);
>> > > > > > >> > > > > }
>> > > > > > >> > > > > return leaderServer;
>> > > > > > >> > > > > }
>> > > > > > >> > > > >
>> > > > > > >> > > > > Edward
>> > > > > > >> > > > >
>> > > > > > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
>> > > > > > >> > > edward.ribeiro@gmail.com
>> > > > > > >> > > > >
>> > > > > > >> > > > > wrote:
>> > > > > > >> > > > >
>> > > > > > >> > > > > > Hi Enrico,
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > Well, I am not an expert on QuorumPeer either (not
>> an
>> > > > expert
>> > > > > > on
>> > > > > > >> > > > anything,
>> > > > > > >> > > > > > really), but maybe it's the variable and method
>> below?
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ----------------- QuorumPeer ------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > /**
>> > > > > > >> > > > > > * This is who I think the leader currently is.
>> > > > > > >> > > > > > */
>> > > > > > >> > > > > > volatile private Vote currentVote;
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > public synchronized Vote getCurrentVote(){
>> > > > > > >> > > > > > return currentVote;
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ---------------------------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > Then it's a matter of calling
>> > > > > > >> quorumPeer.getCurrentVote().getId()
>> > > > > > >> > and
>> > > > > > >> > > > > > quorumPeer.getServerState()?
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > Btw, the Learner class has this handy method below
>> > (self
>> > > > is
>> > > > > a
>> > > > > > >> > > > > QuorumPeer):
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ---------------- Learner --------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > /**
>> > > > > > >> > > > > > * Returns the address of the node we think is the
>> > > leader.
>> > > > > > >> > > > > > */
>> > > > > > >> > > > > > protected QuorumServer findLeader() {
>> > > > > > >> > > > > > QuorumServer leaderServer = null;
>> > > > > > >> > > > > > // Find the leader by id
>> > > > > > >> > > > > > Vote current = self.getCurrentVote();
>> > > > > > >> > > > > > for (QuorumServer s : self.getView().values())
>> {
>> > > > > > >> > > > > > if (s.id == current.getId()) {
>> > > > > > >> > > > > > leaderServer = s;
>> > > > > > >> > > > > > break;
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > > if (leaderServer == null) {
>> > > > > > >> > > > > > LOG.warn("Couldn't find the leader with id
>> = "
>> > > > > > >> > > > > > + current.getId());
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > > return leaderServer;
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ---------------------------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > By the way, as a side note, the map traversal
>> could be
>> > > > > changed
>> > > > > > >> by:
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ----------------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > if (self.getView().contains(current.getId()) {
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > ---------------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > You can see above this method the
>> quorumPeer.getView()
>> > > > > > returns a
>> > > > > > >> > > > Map<sid,
>> > > > > > >> > > > > > QuorumServer> as below:
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > -------------QuorumPeer ---------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > /**
>> > > > > > >> > > > > > * A 'view' is a node's current opinion of the
>> > > membership
>> > > > of
>> > > > > > the
>> > > > > > >> > > entire
>> > > > > > >> > > > > > * ensemble.
>> > > > > > >> > > > > > */
>> > > > > > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView()
>> {
>> > > > > > >> > > > > > return Collections.unmodifiableMap(
>> > > > getQuorumVerifier().
>> > > > > > >> > > > > > getAllMembers());
>> > > > > > >> > > > > > }
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > -----------------------------
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > And then it retrieves the QuorumServer that has
>> many
>> > > more
>> > > > > > >> > information
>> > > > > > >> > > > > > about the node besides the sid (InetSocketAddress,
>> > > > hostname,
>> > > > > > >> etc).
>> > > > > > >> > :)
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > Cheers,
>> > > > > > >> > > > > > Edward
>> > > > > > >> > > > > >
>> > > > > > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
>> > > > > > >> > eolivelli@gmail.com
>> > > > > > >> > > >
>> > > > > > >> > > > > > wrote:
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >> So I am trying to create a patch in order to
>> expose
>> > on
>> > > > JMX
>> > > > > > the
>> > > > > > >> id
>> > > > > > >> > of
>> > > > > > >> > > > the
>> > > > > > >> > > > > >> current "leader" (on the JVM of a follower)
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >> I am trying to find in ZK which is the variable
>> which
>> > > > holds
>> > > > > > >> the ID
>> > > > > > >> > > of
>> > > > > > >> > > > > the
>> > > > > > >> > > > > >> current leader.
>> > > > > > >> > > > > >> I am new to the internal of QuorumPeer
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >> Can someone give me some hint ?
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >> Enrico
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel
>> > > Zandegran <
>> > > > > > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >> > Hi,
>> > > > > > >> > > > > >> > That is possible with 4 letter commands. We are
>> > using
>> > > > it
>> > > > > > >> now. In
>> > > > > > >> > > > 3.5.x
>> > > > > > >> > > > > >> it
>> > > > > > >> > > > > >> > is going to be removed in favour of admin server
>> > > > > (embedded
>> > > > > > >> web
>> > > > > > >> > > > > server).
>> > > > > > >> > > > > >> > We are running in an environment where it’s not
>> > > > possible
>> > > > > to
>> > > > > > >> run
>> > > > > > >> > > JMX
>> > > > > > >> > > > or
>> > > > > > >> > > > > >> > embedded web servers.
>> > > > > > >> > > > > >> >
>> > > > > > >> > > > > >> > So I am wondering if there is another way? It
>> would
>> > > be
>> > > > > nice
>> > > > > > >> to
>> > > > > > >> > > have
>> > > > > > >> > > > > this
>> > > > > > >> > > > > >> > info as a znode.
>> > > > > > >> > > > > >> >
>> > > > > > >> > > > > >> > Best regards,
>> > > > > > >> > > > > >> > Ansel
>> > > > > > >> > > > > >> >
>> > > > > > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
>> > > > > > fpj@apache.org>
>> > > > > > >> > > wrote:
>> > > > > > >> > > > > >> > >
>> > > > > > >> > > > > >> > > Hi Enrico,
>> > > > > > >> > > > > >> > >
>> > > > > > >> > > > > >> > > You can determine the state of a server it via
>> > > > 4-letter
>> > > > > > >> > > commands.
>> > > > > > >> > > > > >> Would
>> > > > > > >> > > > > >> > that work for you?
>> > > > > > >> > > > > >> > >
>> > > > > > >> > > > > >> > > -Flavio
>> > > > > > >> > > > > >> > >
>> > > > > > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
>> > > > > > >> > eolivelli@gmail.com>
>> > > > > > >> > > > > >> wrote:
>> > > > > > >> > > > > >> > >>
>> > > > > > >> > > > > >> > >> Hi,
>> > > > > > >> > > > > >> > >> is there any way to see in JMX which is the
>> > leader
>> > > > of
>> > > > > a
>> > > > > > >> > > ZooKeeper
>> > > > > > >> > > > > >> > cluster?
>> > > > > > >> > > > > >> > >>
>> > > > > > >> > > > > >> > >> My problem is: given access to any of the
>> nodes
>> > of
>> > > > the
>> > > > > > >> > cluster
>> > > > > > >> > > I
>> > > > > > >> > > > > >> want to
>> > > > > > >> > > > > >> > >> know from JMX which is the current leader.
>> > > > > > >> > > > > >> > >> It seems to me that this information is not
>> > > > available,
>> > > > > > you
>> > > > > > >> > can
>> > > > > > >> > > > know
>> > > > > > >> > > > > >> > only if
>> > > > > > >> > > > > >> > >> the local node is Leader or Follower.
>> > > > > > >> > > > > >> > >>
>> > > > > > >> > > > > >> > >> Cheers
>> > > > > > >> > > > > >> > >> Enrico
>> > > > > > >> > > > > >> > >
>> > > > > > >> > > > > >> >
>> > > > > > >> > > > > >> >
>> > > > > > >> > > > > >>
>> > > > > > >> > > > > >
>> > > > > > >> > > > > >
>> > > > > > >> > > > >
>> > > > > > >> > > >
>> > > > > > >> > >
>> > > > > > >> >
>> > > > > > >>
>> > > > > > > --
>> > > > > > >
>> > > > > > >
>> > > > > > > -- Enrico Olivelli
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> > --
>> >
>> >
>> > -- Enrico Olivelli
>> >
>>
> --
>
>
> -- Enrico Olivelli
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Il gio 21 giu 2018, 17:13 Andor Molnar <an...@cloudera.com.invalid> ha
scritto:
> Okay, let's put it this way: what kind of test would you like to add here?
>
> *Unit test*
> This is a requirement for the patch to be committed. You don't need to fire
> up a full blown ensemble to test the new functionality. Pick the class that
> you'd like to test, mock out the dependencies with moquito and write some
> quick unit tests. Your tests should finish in a few hundreds millisecs (1-2
> secs maximum).
>
This is achieved in my patch. There was already a test about JMX and
LocalPeerMXBean. I have enhanced it, by extending the test to cover my new
JMX attribute and, to cover even RemotePeerMXBean, which was not tested at
all.
One review comment asked me to perform assertions after a leadership change.
I did not touch ZK internals with this patch, I am only publishing internal
state to JMX endpoint.
Maybe what I am trying to do is not needed for the patch to be 'acceptable'.
I think it would be useful to add such test case, but not strictly needed.
Unfortunately current test utilities seem to able to do what requested.
I am able to add mockito based tests if requested.
> *Integration test*
> This is not required, but more than welcome. Can you do it with reasonable
> amount of effort? Is it going to finish in an acceptable time frame (5-10
> secs)? If yes, go ahead, if not, skip that.
>
Not needed. Maybe existing test case is already similar to an integration
test ( it brings up a cluster of 5 nodes).
Anyway my changes is not slowing down the full suite add I am only adding
an assertion to an existing old test.
I think the restart of the cluster it is not strictly needed and it will
may add a new flaky test.
Treating ZK as one of my projects, I think the existing JMX test corpus
should be refactored but given the little impact of this patch is it not
worth to spend much time.
Enrico
> Hope that helps.
>
> Regards,
> Andor
>
>
>
>
>
>
> On Thu, Jun 21, 2018 at 2:39 PM, Enrico Olivelli <eo...@gmail.com>
> wrote:
>
> > Andor,
> >
> > I had already tried that way but without success.
> > I have updated the patch with a proposal.
> > Thanks
> >
> > Enrico
> >
> > Il gio 21 giu 2018, 13:20 Andor Molnar <an...@cloudera.com.invalid> ha
> > scritto:
> >
> > > Hi Enrico!
> > >
> > > Take a look at testElectionFraud(), it might be useful to you.
> > >
> > > Regards,
> > > Andor
> > >
> > >
> > >
> > > On Thu, Jun 21, 2018 at 12:00 PM, Enrico Olivelli <eolivelli@gmail.com
> >
> > > wrote:
> > >
> > > > Norbert,
> > > > thank you for taking a look
> > > >
> > > > Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
> > > > <nk...@cloudera.com.invalid> ha scritto:
> > > >
> > > > > Good question. Wouldn't just killing the leader do the job?
> > > > >
> > > >
> > > > It seems to me that is it not "immediate" to "kill" a QuorumPeer
> inside
> > > > such test.
> > > > If you "shutdown" it you cannot 'start' it anymore.
> > > >
> > > > This is why I am asking for help.
> > > >
> > > > -- Enrico
> > > >
> > > >
> > > >
> > > > >
> > > > > Regards,
> > > > > Norbert
> > > > >
> > > > > On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <
> eolivelli@gmail.com
> > >
> > > > > wrote:
> > > > >
> > > > > > This is my patch
> > > > > > https://github.com/apache/zookeeper/pull/546
> > > > > >
> > > > > > One question:
> > > > > > I would like to force the cluster to change leader in
> > > > > > HierarchicalQuorumTest, so that I can test that JMX will reflect
> > the
> > > > new
> > > > > > status of the group.
> > > > > > Any idea about how to bounce the leader ?
> > > > > >
> > > > > > Cheers
> > > > > > Enrico
> > > > > >
> > > > > > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> > > > > > eolivelli@gmail.com> ha scritto:
> > > > > >
> > > > > > > This is my JIRA
> > > > > > > I am going to work on a patch
> > > > > > >
> > > > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> > > > > > >
> > > > > > > Enrico
> > > > > > >
> > > > > > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha
> > > > > scritto:
> > > > > > >
> > > > > > >> "in order to guess which is the leader I have to ask to all of
> > the
> > > > > three
> > > > > > >> nodes in the cluster"
> > > > > > >>
> > > > > > >> That's correct.
> > > > > > >>
> > > > > > >> Regards,
> > > > > > >> Andor
> > > > > > >>
> > > > > > >>
> > > > > > >>
> > > > > > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <
> > > > eolivelli@gmail.com
> > > > > >
> > > > > > >> wrote:
> > > > > > >>
> > > > > > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> > > > > > phunt@apache.org>
> > > > > > >> ha
> > > > > > >> > scritto:
> > > > > > >> >
> > > > > > >> > > iiuc what you are interested in the information is already
> > > > > > available.
> > > > > > >> The
> > > > > > >> > > beans have a "state" attribute which indicates following
> vs
> > > > > leading.
> > > > > > >> > >
> > > > > > >> > > Try attaching a jconsole to the running servers, use the
> > > > "mbeans"
> > > > > > tab
> > > > > > >> and
> > > > > > >> > > open org.apache.ZooKeeperService -> replicatedserver ->
> > > replica
> > > > ->
> > > > > > >> > > attributes, you'll see the "state" attribute there.
> > > > > > >> > >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> > Patrick,
> > > > > > >> > I can't find this information.
> > > > > > >> > If I log into a "follower" I get this info only for the
> > 'current
> > > > > > >> replica'
> > > > > > >> >
> > > > > > >> > Example, I have three peers, the first one is a "Follower",
> > on
> > > > JMX
> > > > > I
> > > > > > >> have
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > > ClientAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > > >> ElectionAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > LearnerType
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > Name
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > > QuorumAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > State =
> > > > > > >> > following
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > > ConfigVersion
> > > > > > >> > .....
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> > for other peers I see only
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > > ClientAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > > >> ElectionAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > LearnerType
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > Name
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > > QuorumAddress
> > > > > > >> >
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > > ClientAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > > >> ElectionAddress
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > LearnerType
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > Name
> > > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > > QuorumAddress
> > > > > > >> >
> > > > > > >> >
> > > > > > >> > so quering only this server I cannot guess which is the
> > current
> > > > > > leader,
> > > > > > >> the
> > > > > > >> > only information I can extract is:
> > > > > > >> > - I am a follower
> > > > > > >> > - We are a cluster of three
> > > > > > >> > - Every of the three is a PARTECIPANT (no observers)
> > > > > > >> >
> > > > > > >> > in order to guess which is the leader I have to ask to all
> of
> > > the
> > > > > > three
> > > > > > >> > nodes in the cluster
> > > > > > >> >
> > > > > > >> > Am I missing something ? I am running 3.5.3-BETA
> > > > > > >> >
> > > > > > >> > Enrico
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> >
> > > > > > >> > >
> > > > > > >> > > Patrick
> > > > > > >> > >
> > > > > > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> > > > > > eolivelli@gmail.com>
> > > > > > >> > > wrote:
> > > > > > >> > >
> > > > > > >> > > > Thank you Edward
> > > > > > >> > > >
> > > > > > >> > > > I will pack all together and send out a patch as soon
> as I
> > > > have
> > > > > > >> time.
> > > > > > >> > > > I am running 3.5 in production and given than an RC for
> > > 3.5.4
> > > > is
> > > > > > >> going
> > > > > > >> > to
> > > > > > >> > > > be cut soon I will have to wait for 3.5.5 and I assume
> it
> > > > won't
> > > > > be
> > > > > > >> > > > immediate.
> > > > > > >> > > >
> > > > > > >> > > > Cheers
> > > > > > >> > > > Enrico
> > > > > > >> > > >
> > > > > > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > > > > >> > > > edward.ribeiro@gmail.com> ha scritto:
> > > > > > >> > > >
> > > > > > >> > > > > Sent before finishing the previous email. Only to
> > > > complement,
> > > > > > the
> > > > > > >> > > > > findLeader() could have been as below, but this change
> > is
> > > > > only a
> > > > > > >> > nitty
> > > > > > >> > > > > detail and totally irrelevant to the questions you are
> > > > asking.
> > > > > > :)
> > > > > > >> > > > >
> > > > > > >> > > > > /**
> > > > > > >> > > > > * Returns the address of the node we think is the
> > leader.
> > > > > > >> > > > > */
> > > > > > >> > > > > protected QuorumServer findLeader() {
> > > > > > >> > > > >
> > > > > > >> > > > > // Find the leader by id
> > > > > > >> > > > > long currentLeader =
> self.getCurrentVote().getId();
> > > > > > >> > > > >
> > > > > > >> > > > > QuorumServer leaderServer =
> > > > > > self.getView().get(currentLeader);
> > > > > > >> > > > >
> > > > > > >> > > > > if (leaderServer == null) {
> > > > > > >> > > > > LOG.warn("Couldn't find the leader with id =
> > {}",
> > > > > > >> > > currentLeader);
> > > > > > >> > > > > }
> > > > > > >> > > > > return leaderServer;
> > > > > > >> > > > > }
> > > > > > >> > > > >
> > > > > > >> > > > > Edward
> > > > > > >> > > > >
> > > > > > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > > > > > >> > > edward.ribeiro@gmail.com
> > > > > > >> > > > >
> > > > > > >> > > > > wrote:
> > > > > > >> > > > >
> > > > > > >> > > > > > Hi Enrico,
> > > > > > >> > > > > >
> > > > > > >> > > > > > Well, I am not an expert on QuorumPeer either (not
> an
> > > > expert
> > > > > > on
> > > > > > >> > > > anything,
> > > > > > >> > > > > > really), but maybe it's the variable and method
> below?
> > > > > > >> > > > > >
> > > > > > >> > > > > > ----------------- QuorumPeer ------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > > /**
> > > > > > >> > > > > > * This is who I think the leader currently is.
> > > > > > >> > > > > > */
> > > > > > >> > > > > > volatile private Vote currentVote;
> > > > > > >> > > > > >
> > > > > > >> > > > > > public synchronized Vote getCurrentVote(){
> > > > > > >> > > > > > return currentVote;
> > > > > > >> > > > > > }
> > > > > > >> > > > > >
> > > > > > >> > > > > > ---------------------------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > > > Then it's a matter of calling
> > > > > > >> quorumPeer.getCurrentVote().getId()
> > > > > > >> > and
> > > > > > >> > > > > > quorumPeer.getServerState()?
> > > > > > >> > > > > >
> > > > > > >> > > > > > Btw, the Learner class has this handy method below
> > (self
> > > > is
> > > > > a
> > > > > > >> > > > > QuorumPeer):
> > > > > > >> > > > > >
> > > > > > >> > > > > > ---------------- Learner --------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > > /**
> > > > > > >> > > > > > * Returns the address of the node we think is the
> > > leader.
> > > > > > >> > > > > > */
> > > > > > >> > > > > > protected QuorumServer findLeader() {
> > > > > > >> > > > > > QuorumServer leaderServer = null;
> > > > > > >> > > > > > // Find the leader by id
> > > > > > >> > > > > > Vote current = self.getCurrentVote();
> > > > > > >> > > > > > for (QuorumServer s : self.getView().values()) {
> > > > > > >> > > > > > if (s.id == current.getId()) {
> > > > > > >> > > > > > leaderServer = s;
> > > > > > >> > > > > > break;
> > > > > > >> > > > > > }
> > > > > > >> > > > > > }
> > > > > > >> > > > > > if (leaderServer == null) {
> > > > > > >> > > > > > LOG.warn("Couldn't find the leader with id
> = "
> > > > > > >> > > > > > + current.getId());
> > > > > > >> > > > > > }
> > > > > > >> > > > > > return leaderServer;
> > > > > > >> > > > > > }
> > > > > > >> > > > > >
> > > > > > >> > > > > > ---------------------------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > > By the way, as a side note, the map traversal could
> be
> > > > > changed
> > > > > > >> by:
> > > > > > >> > > > > >
> > > > > > >> > > > > > ----------------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > > if (self.getView().contains(current.getId()) {
> > > > > > >> > > > > >
> > > > > > >> > > > > > }
> > > > > > >> > > > > >
> > > > > > >> > > > > > ---------------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > > > You can see above this method the
> quorumPeer.getView()
> > > > > > returns a
> > > > > > >> > > > Map<sid,
> > > > > > >> > > > > > QuorumServer> as below:
> > > > > > >> > > > > >
> > > > > > >> > > > > > -------------QuorumPeer ---------
> > > > > > >> > > > > >
> > > > > > >> > > > > > /**
> > > > > > >> > > > > > * A 'view' is a node's current opinion of the
> > > membership
> > > > of
> > > > > > the
> > > > > > >> > > entire
> > > > > > >> > > > > > * ensemble.
> > > > > > >> > > > > > */
> > > > > > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > > > >> > > > > > return Collections.unmodifiableMap(
> > > > getQuorumVerifier().
> > > > > > >> > > > > > getAllMembers());
> > > > > > >> > > > > > }
> > > > > > >> > > > > >
> > > > > > >> > > > > > -----------------------------
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > > > And then it retrieves the QuorumServer that has many
> > > more
> > > > > > >> > information
> > > > > > >> > > > > > about the node besides the sid (InetSocketAddress,
> > > > hostname,
> > > > > > >> etc).
> > > > > > >> > :)
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > > > Cheers,
> > > > > > >> > > > > > Edward
> > > > > > >> > > > > >
> > > > > > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > > > > > >> > eolivelli@gmail.com
> > > > > > >> > > >
> > > > > > >> > > > > > wrote:
> > > > > > >> > > > > >
> > > > > > >> > > > > >> So I am trying to create a patch in order to expose
> > on
> > > > JMX
> > > > > > the
> > > > > > >> id
> > > > > > >> > of
> > > > > > >> > > > the
> > > > > > >> > > > > >> current "leader" (on the JVM of a follower)
> > > > > > >> > > > > >>
> > > > > > >> > > > > >> I am trying to find in ZK which is the variable
> which
> > > > holds
> > > > > > >> the ID
> > > > > > >> > > of
> > > > > > >> > > > > the
> > > > > > >> > > > > >> current leader.
> > > > > > >> > > > > >> I am new to the internal of QuorumPeer
> > > > > > >> > > > > >>
> > > > > > >> > > > > >> Can someone give me some hint ?
> > > > > > >> > > > > >>
> > > > > > >> > > > > >> Enrico
> > > > > > >> > > > > >>
> > > > > > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel
> > > Zandegran <
> > > > > > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > > > >> > > > > >>
> > > > > > >> > > > > >> > Hi,
> > > > > > >> > > > > >> > That is possible with 4 letter commands. We are
> > using
> > > > it
> > > > > > >> now. In
> > > > > > >> > > > 3.5.x
> > > > > > >> > > > > >> it
> > > > > > >> > > > > >> > is going to be removed in favour of admin server
> > > > > (embedded
> > > > > > >> web
> > > > > > >> > > > > server).
> > > > > > >> > > > > >> > We are running in an environment where it’s not
> > > > possible
> > > > > to
> > > > > > >> run
> > > > > > >> > > JMX
> > > > > > >> > > > or
> > > > > > >> > > > > >> > embedded web servers.
> > > > > > >> > > > > >> >
> > > > > > >> > > > > >> > So I am wondering if there is another way? It
> would
> > > be
> > > > > nice
> > > > > > >> to
> > > > > > >> > > have
> > > > > > >> > > > > this
> > > > > > >> > > > > >> > info as a znode.
> > > > > > >> > > > > >> >
> > > > > > >> > > > > >> > Best regards,
> > > > > > >> > > > > >> > Ansel
> > > > > > >> > > > > >> >
> > > > > > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> > > > > > fpj@apache.org>
> > > > > > >> > > wrote:
> > > > > > >> > > > > >> > >
> > > > > > >> > > > > >> > > Hi Enrico,
> > > > > > >> > > > > >> > >
> > > > > > >> > > > > >> > > You can determine the state of a server it via
> > > > 4-letter
> > > > > > >> > > commands.
> > > > > > >> > > > > >> Would
> > > > > > >> > > > > >> > that work for you?
> > > > > > >> > > > > >> > >
> > > > > > >> > > > > >> > > -Flavio
> > > > > > >> > > > > >> > >
> > > > > > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > > > > > >> > eolivelli@gmail.com>
> > > > > > >> > > > > >> wrote:
> > > > > > >> > > > > >> > >>
> > > > > > >> > > > > >> > >> Hi,
> > > > > > >> > > > > >> > >> is there any way to see in JMX which is the
> > leader
> > > > of
> > > > > a
> > > > > > >> > > ZooKeeper
> > > > > > >> > > > > >> > cluster?
> > > > > > >> > > > > >> > >>
> > > > > > >> > > > > >> > >> My problem is: given access to any of the
> nodes
> > of
> > > > the
> > > > > > >> > cluster
> > > > > > >> > > I
> > > > > > >> > > > > >> want to
> > > > > > >> > > > > >> > >> know from JMX which is the current leader.
> > > > > > >> > > > > >> > >> It seems to me that this information is not
> > > > available,
> > > > > > you
> > > > > > >> > can
> > > > > > >> > > > know
> > > > > > >> > > > > >> > only if
> > > > > > >> > > > > >> > >> the local node is Leader or Follower.
> > > > > > >> > > > > >> > >>
> > > > > > >> > > > > >> > >> Cheers
> > > > > > >> > > > > >> > >> Enrico
> > > > > > >> > > > > >> > >
> > > > > > >> > > > > >> >
> > > > > > >> > > > > >> >
> > > > > > >> > > > > >>
> > > > > > >> > > > > >
> > > > > > >> > > > > >
> > > > > > >> > > > >
> > > > > > >> > > >
> > > > > > >> > >
> > > > > > >> >
> > > > > > >>
> > > > > > > --
> > > > > > >
> > > > > > >
> > > > > > > -- Enrico Olivelli
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> > --
> >
> >
> > -- Enrico Olivelli
> >
>
--
-- Enrico Olivelli
Re: Discover LEADER from JMX
Posted by Andor Molnar <an...@cloudera.com.INVALID>.
Okay, let's put it this way: what kind of test would you like to add here?
*Unit test*
This is a requirement for the patch to be committed. You don't need to fire
up a full blown ensemble to test the new functionality. Pick the class that
you'd like to test, mock out the dependencies with moquito and write some
quick unit tests. Your tests should finish in a few hundreds millisecs (1-2
secs maximum).
*Integration test*
This is not required, but more than welcome. Can you do it with reasonable
amount of effort? Is it going to finish in an acceptable time frame (5-10
secs)? If yes, go ahead, if not, skip that.
Hope that helps.
Regards,
Andor
On Thu, Jun 21, 2018 at 2:39 PM, Enrico Olivelli <eo...@gmail.com>
wrote:
> Andor,
>
> I had already tried that way but without success.
> I have updated the patch with a proposal.
> Thanks
>
> Enrico
>
> Il gio 21 giu 2018, 13:20 Andor Molnar <an...@cloudera.com.invalid> ha
> scritto:
>
> > Hi Enrico!
> >
> > Take a look at testElectionFraud(), it might be useful to you.
> >
> > Regards,
> > Andor
> >
> >
> >
> > On Thu, Jun 21, 2018 at 12:00 PM, Enrico Olivelli <eo...@gmail.com>
> > wrote:
> >
> > > Norbert,
> > > thank you for taking a look
> > >
> > > Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
> > > <nk...@cloudera.com.invalid> ha scritto:
> > >
> > > > Good question. Wouldn't just killing the leader do the job?
> > > >
> > >
> > > It seems to me that is it not "immediate" to "kill" a QuorumPeer inside
> > > such test.
> > > If you "shutdown" it you cannot 'start' it anymore.
> > >
> > > This is why I am asking for help.
> > >
> > > -- Enrico
> > >
> > >
> > >
> > > >
> > > > Regards,
> > > > Norbert
> > > >
> > > > On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <eolivelli@gmail.com
> >
> > > > wrote:
> > > >
> > > > > This is my patch
> > > > > https://github.com/apache/zookeeper/pull/546
> > > > >
> > > > > One question:
> > > > > I would like to force the cluster to change leader in
> > > > > HierarchicalQuorumTest, so that I can test that JMX will reflect
> the
> > > new
> > > > > status of the group.
> > > > > Any idea about how to bounce the leader ?
> > > > >
> > > > > Cheers
> > > > > Enrico
> > > > >
> > > > > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> > > > > eolivelli@gmail.com> ha scritto:
> > > > >
> > > > > > This is my JIRA
> > > > > > I am going to work on a patch
> > > > > >
> > > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> > > > > >
> > > > > > Enrico
> > > > > >
> > > > > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha
> > > > scritto:
> > > > > >
> > > > > >> "in order to guess which is the leader I have to ask to all of
> the
> > > > three
> > > > > >> nodes in the cluster"
> > > > > >>
> > > > > >> That's correct.
> > > > > >>
> > > > > >> Regards,
> > > > > >> Andor
> > > > > >>
> > > > > >>
> > > > > >>
> > > > > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <
> > > eolivelli@gmail.com
> > > > >
> > > > > >> wrote:
> > > > > >>
> > > > > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> > > > > phunt@apache.org>
> > > > > >> ha
> > > > > >> > scritto:
> > > > > >> >
> > > > > >> > > iiuc what you are interested in the information is already
> > > > > available.
> > > > > >> The
> > > > > >> > > beans have a "state" attribute which indicates following vs
> > > > leading.
> > > > > >> > >
> > > > > >> > > Try attaching a jconsole to the running servers, use the
> > > "mbeans"
> > > > > tab
> > > > > >> and
> > > > > >> > > open org.apache.ZooKeeperService -> replicatedserver ->
> > replica
> > > ->
> > > > > >> > > attributes, you'll see the "state" attribute there.
> > > > > >> > >
> > > > > >> >
> > > > > >> >
> > > > > >> > Patrick,
> > > > > >> > I can't find this information.
> > > > > >> > If I log into a "follower" I get this info only for the
> 'current
> > > > > >> replica'
> > > > > >> >
> > > > > >> > Example, I have three peers, the first one is a "Follower",
> on
> > > JMX
> > > > I
> > > > > >> have
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > ClientAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > >> ElectionAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > LearnerType
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> Name
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > QuorumAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > State =
> > > > > >> > following
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > > ConfigVersion
> > > > > >> > .....
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> > for other peers I see only
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > ClientAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > >> ElectionAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > LearnerType
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> Name
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > > QuorumAddress
> > > > > >> >
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > ClientAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > >> ElectionAddress
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > LearnerType
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> Name
> > > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > > QuorumAddress
> > > > > >> >
> > > > > >> >
> > > > > >> > so quering only this server I cannot guess which is the
> current
> > > > > leader,
> > > > > >> the
> > > > > >> > only information I can extract is:
> > > > > >> > - I am a follower
> > > > > >> > - We are a cluster of three
> > > > > >> > - Every of the three is a PARTECIPANT (no observers)
> > > > > >> >
> > > > > >> > in order to guess which is the leader I have to ask to all of
> > the
> > > > > three
> > > > > >> > nodes in the cluster
> > > > > >> >
> > > > > >> > Am I missing something ? I am running 3.5.3-BETA
> > > > > >> >
> > > > > >> > Enrico
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> >
> > > > > >> > >
> > > > > >> > > Patrick
> > > > > >> > >
> > > > > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> > > > > eolivelli@gmail.com>
> > > > > >> > > wrote:
> > > > > >> > >
> > > > > >> > > > Thank you Edward
> > > > > >> > > >
> > > > > >> > > > I will pack all together and send out a patch as soon as I
> > > have
> > > > > >> time.
> > > > > >> > > > I am running 3.5 in production and given than an RC for
> > 3.5.4
> > > is
> > > > > >> going
> > > > > >> > to
> > > > > >> > > > be cut soon I will have to wait for 3.5.5 and I assume it
> > > won't
> > > > be
> > > > > >> > > > immediate.
> > > > > >> > > >
> > > > > >> > > > Cheers
> > > > > >> > > > Enrico
> > > > > >> > > >
> > > > > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > > > >> > > > edward.ribeiro@gmail.com> ha scritto:
> > > > > >> > > >
> > > > > >> > > > > Sent before finishing the previous email. Only to
> > > complement,
> > > > > the
> > > > > >> > > > > findLeader() could have been as below, but this change
> is
> > > > only a
> > > > > >> > nitty
> > > > > >> > > > > detail and totally irrelevant to the questions you are
> > > asking.
> > > > > :)
> > > > > >> > > > >
> > > > > >> > > > > /**
> > > > > >> > > > > * Returns the address of the node we think is the
> leader.
> > > > > >> > > > > */
> > > > > >> > > > > protected QuorumServer findLeader() {
> > > > > >> > > > >
> > > > > >> > > > > // Find the leader by id
> > > > > >> > > > > long currentLeader = self.getCurrentVote().getId();
> > > > > >> > > > >
> > > > > >> > > > > QuorumServer leaderServer =
> > > > > self.getView().get(currentLeader);
> > > > > >> > > > >
> > > > > >> > > > > if (leaderServer == null) {
> > > > > >> > > > > LOG.warn("Couldn't find the leader with id =
> {}",
> > > > > >> > > currentLeader);
> > > > > >> > > > > }
> > > > > >> > > > > return leaderServer;
> > > > > >> > > > > }
> > > > > >> > > > >
> > > > > >> > > > > Edward
> > > > > >> > > > >
> > > > > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > > > > >> > > edward.ribeiro@gmail.com
> > > > > >> > > > >
> > > > > >> > > > > wrote:
> > > > > >> > > > >
> > > > > >> > > > > > Hi Enrico,
> > > > > >> > > > > >
> > > > > >> > > > > > Well, I am not an expert on QuorumPeer either (not an
> > > expert
> > > > > on
> > > > > >> > > > anything,
> > > > > >> > > > > > really), but maybe it's the variable and method below?
> > > > > >> > > > > >
> > > > > >> > > > > > ----------------- QuorumPeer ------------------
> > > > > >> > > > > >
> > > > > >> > > > > > /**
> > > > > >> > > > > > * This is who I think the leader currently is.
> > > > > >> > > > > > */
> > > > > >> > > > > > volatile private Vote currentVote;
> > > > > >> > > > > >
> > > > > >> > > > > > public synchronized Vote getCurrentVote(){
> > > > > >> > > > > > return currentVote;
> > > > > >> > > > > > }
> > > > > >> > > > > >
> > > > > >> > > > > > ---------------------------------------
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > > > Then it's a matter of calling
> > > > > >> quorumPeer.getCurrentVote().getId()
> > > > > >> > and
> > > > > >> > > > > > quorumPeer.getServerState()?
> > > > > >> > > > > >
> > > > > >> > > > > > Btw, the Learner class has this handy method below
> (self
> > > is
> > > > a
> > > > > >> > > > > QuorumPeer):
> > > > > >> > > > > >
> > > > > >> > > > > > ---------------- Learner --------------------
> > > > > >> > > > > >
> > > > > >> > > > > > /**
> > > > > >> > > > > > * Returns the address of the node we think is the
> > leader.
> > > > > >> > > > > > */
> > > > > >> > > > > > protected QuorumServer findLeader() {
> > > > > >> > > > > > QuorumServer leaderServer = null;
> > > > > >> > > > > > // Find the leader by id
> > > > > >> > > > > > Vote current = self.getCurrentVote();
> > > > > >> > > > > > for (QuorumServer s : self.getView().values()) {
> > > > > >> > > > > > if (s.id == current.getId()) {
> > > > > >> > > > > > leaderServer = s;
> > > > > >> > > > > > break;
> > > > > >> > > > > > }
> > > > > >> > > > > > }
> > > > > >> > > > > > if (leaderServer == null) {
> > > > > >> > > > > > LOG.warn("Couldn't find the leader with id = "
> > > > > >> > > > > > + current.getId());
> > > > > >> > > > > > }
> > > > > >> > > > > > return leaderServer;
> > > > > >> > > > > > }
> > > > > >> > > > > >
> > > > > >> > > > > > ---------------------------------------
> > > > > >> > > > > >
> > > > > >> > > > > > By the way, as a side note, the map traversal could be
> > > > changed
> > > > > >> by:
> > > > > >> > > > > >
> > > > > >> > > > > > ----------------------------
> > > > > >> > > > > >
> > > > > >> > > > > > if (self.getView().contains(current.getId()) {
> > > > > >> > > > > >
> > > > > >> > > > > > }
> > > > > >> > > > > >
> > > > > >> > > > > > ---------------------------
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > > > You can see above this method the quorumPeer.getView()
> > > > > returns a
> > > > > >> > > > Map<sid,
> > > > > >> > > > > > QuorumServer> as below:
> > > > > >> > > > > >
> > > > > >> > > > > > -------------QuorumPeer ---------
> > > > > >> > > > > >
> > > > > >> > > > > > /**
> > > > > >> > > > > > * A 'view' is a node's current opinion of the
> > membership
> > > of
> > > > > the
> > > > > >> > > entire
> > > > > >> > > > > > * ensemble.
> > > > > >> > > > > > */
> > > > > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > > >> > > > > > return Collections.unmodifiableMap(
> > > getQuorumVerifier().
> > > > > >> > > > > > getAllMembers());
> > > > > >> > > > > > }
> > > > > >> > > > > >
> > > > > >> > > > > > -----------------------------
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > > > And then it retrieves the QuorumServer that has many
> > more
> > > > > >> > information
> > > > > >> > > > > > about the node besides the sid (InetSocketAddress,
> > > hostname,
> > > > > >> etc).
> > > > > >> > :)
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > > > Cheers,
> > > > > >> > > > > > Edward
> > > > > >> > > > > >
> > > > > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > > > > >> > eolivelli@gmail.com
> > > > > >> > > >
> > > > > >> > > > > > wrote:
> > > > > >> > > > > >
> > > > > >> > > > > >> So I am trying to create a patch in order to expose
> on
> > > JMX
> > > > > the
> > > > > >> id
> > > > > >> > of
> > > > > >> > > > the
> > > > > >> > > > > >> current "leader" (on the JVM of a follower)
> > > > > >> > > > > >>
> > > > > >> > > > > >> I am trying to find in ZK which is the variable which
> > > holds
> > > > > >> the ID
> > > > > >> > > of
> > > > > >> > > > > the
> > > > > >> > > > > >> current leader.
> > > > > >> > > > > >> I am new to the internal of QuorumPeer
> > > > > >> > > > > >>
> > > > > >> > > > > >> Can someone give me some hint ?
> > > > > >> > > > > >>
> > > > > >> > > > > >> Enrico
> > > > > >> > > > > >>
> > > > > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel
> > Zandegran <
> > > > > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > > >> > > > > >>
> > > > > >> > > > > >> > Hi,
> > > > > >> > > > > >> > That is possible with 4 letter commands. We are
> using
> > > it
> > > > > >> now. In
> > > > > >> > > > 3.5.x
> > > > > >> > > > > >> it
> > > > > >> > > > > >> > is going to be removed in favour of admin server
> > > > (embedded
> > > > > >> web
> > > > > >> > > > > server).
> > > > > >> > > > > >> > We are running in an environment where it’s not
> > > possible
> > > > to
> > > > > >> run
> > > > > >> > > JMX
> > > > > >> > > > or
> > > > > >> > > > > >> > embedded web servers.
> > > > > >> > > > > >> >
> > > > > >> > > > > >> > So I am wondering if there is another way? It would
> > be
> > > > nice
> > > > > >> to
> > > > > >> > > have
> > > > > >> > > > > this
> > > > > >> > > > > >> > info as a znode.
> > > > > >> > > > > >> >
> > > > > >> > > > > >> > Best regards,
> > > > > >> > > > > >> > Ansel
> > > > > >> > > > > >> >
> > > > > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> > > > > fpj@apache.org>
> > > > > >> > > wrote:
> > > > > >> > > > > >> > >
> > > > > >> > > > > >> > > Hi Enrico,
> > > > > >> > > > > >> > >
> > > > > >> > > > > >> > > You can determine the state of a server it via
> > > 4-letter
> > > > > >> > > commands.
> > > > > >> > > > > >> Would
> > > > > >> > > > > >> > that work for you?
> > > > > >> > > > > >> > >
> > > > > >> > > > > >> > > -Flavio
> > > > > >> > > > > >> > >
> > > > > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > > > > >> > eolivelli@gmail.com>
> > > > > >> > > > > >> wrote:
> > > > > >> > > > > >> > >>
> > > > > >> > > > > >> > >> Hi,
> > > > > >> > > > > >> > >> is there any way to see in JMX which is the
> leader
> > > of
> > > > a
> > > > > >> > > ZooKeeper
> > > > > >> > > > > >> > cluster?
> > > > > >> > > > > >> > >>
> > > > > >> > > > > >> > >> My problem is: given access to any of the nodes
> of
> > > the
> > > > > >> > cluster
> > > > > >> > > I
> > > > > >> > > > > >> want to
> > > > > >> > > > > >> > >> know from JMX which is the current leader.
> > > > > >> > > > > >> > >> It seems to me that this information is not
> > > available,
> > > > > you
> > > > > >> > can
> > > > > >> > > > know
> > > > > >> > > > > >> > only if
> > > > > >> > > > > >> > >> the local node is Leader or Follower.
> > > > > >> > > > > >> > >>
> > > > > >> > > > > >> > >> Cheers
> > > > > >> > > > > >> > >> Enrico
> > > > > >> > > > > >> > >
> > > > > >> > > > > >> >
> > > > > >> > > > > >> >
> > > > > >> > > > > >>
> > > > > >> > > > > >
> > > > > >> > > > > >
> > > > > >> > > > >
> > > > > >> > > >
> > > > > >> > >
> > > > > >> >
> > > > > >>
> > > > > > --
> > > > > >
> > > > > >
> > > > > > -- Enrico Olivelli
> > > > > >
> > > > >
> > > >
> > >
> >
> --
>
>
> -- Enrico Olivelli
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Andor,
I had already tried that way but without success.
I have updated the patch with a proposal.
Thanks
Enrico
Il gio 21 giu 2018, 13:20 Andor Molnar <an...@cloudera.com.invalid> ha
scritto:
> Hi Enrico!
>
> Take a look at testElectionFraud(), it might be useful to you.
>
> Regards,
> Andor
>
>
>
> On Thu, Jun 21, 2018 at 12:00 PM, Enrico Olivelli <eo...@gmail.com>
> wrote:
>
> > Norbert,
> > thank you for taking a look
> >
> > Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
> > <nk...@cloudera.com.invalid> ha scritto:
> >
> > > Good question. Wouldn't just killing the leader do the job?
> > >
> >
> > It seems to me that is it not "immediate" to "kill" a QuorumPeer inside
> > such test.
> > If you "shutdown" it you cannot 'start' it anymore.
> >
> > This is why I am asking for help.
> >
> > -- Enrico
> >
> >
> >
> > >
> > > Regards,
> > > Norbert
> > >
> > > On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <eo...@gmail.com>
> > > wrote:
> > >
> > > > This is my patch
> > > > https://github.com/apache/zookeeper/pull/546
> > > >
> > > > One question:
> > > > I would like to force the cluster to change leader in
> > > > HierarchicalQuorumTest, so that I can test that JMX will reflect the
> > new
> > > > status of the group.
> > > > Any idea about how to bounce the leader ?
> > > >
> > > > Cheers
> > > > Enrico
> > > >
> > > > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> > > > eolivelli@gmail.com> ha scritto:
> > > >
> > > > > This is my JIRA
> > > > > I am going to work on a patch
> > > > >
> > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> > > > >
> > > > > Enrico
> > > > >
> > > > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha
> > > scritto:
> > > > >
> > > > >> "in order to guess which is the leader I have to ask to all of the
> > > three
> > > > >> nodes in the cluster"
> > > > >>
> > > > >> That's correct.
> > > > >>
> > > > >> Regards,
> > > > >> Andor
> > > > >>
> > > > >>
> > > > >>
> > > > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <
> > eolivelli@gmail.com
> > > >
> > > > >> wrote:
> > > > >>
> > > > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> > > > phunt@apache.org>
> > > > >> ha
> > > > >> > scritto:
> > > > >> >
> > > > >> > > iiuc what you are interested in the information is already
> > > > available.
> > > > >> The
> > > > >> > > beans have a "state" attribute which indicates following vs
> > > leading.
> > > > >> > >
> > > > >> > > Try attaching a jconsole to the running servers, use the
> > "mbeans"
> > > > tab
> > > > >> and
> > > > >> > > open org.apache.ZooKeeperService -> replicatedserver ->
> replica
> > ->
> > > > >> > > attributes, you'll see the "state" attribute there.
> > > > >> > >
> > > > >> >
> > > > >> >
> > > > >> > Patrick,
> > > > >> > I can't find this information.
> > > > >> > If I log into a "follower" I get this info only for the 'current
> > > > >> replica'
> > > > >> >
> > > > >> > Example, I have three peers, the first one is a "Follower", on
> > JMX
> > > I
> > > > >> have
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > ClientAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > >> ElectionAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > LearnerType
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > QuorumAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> State =
> > > > >> > following
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > > ConfigVersion
> > > > >> > .....
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> > for other peers I see only
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > ClientAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > >> ElectionAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > LearnerType
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > > QuorumAddress
> > > > >> >
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > ClientAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > >> ElectionAddress
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > LearnerType
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> > > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > > QuorumAddress
> > > > >> >
> > > > >> >
> > > > >> > so quering only this server I cannot guess which is the current
> > > > leader,
> > > > >> the
> > > > >> > only information I can extract is:
> > > > >> > - I am a follower
> > > > >> > - We are a cluster of three
> > > > >> > - Every of the three is a PARTECIPANT (no observers)
> > > > >> >
> > > > >> > in order to guess which is the leader I have to ask to all of
> the
> > > > three
> > > > >> > nodes in the cluster
> > > > >> >
> > > > >> > Am I missing something ? I am running 3.5.3-BETA
> > > > >> >
> > > > >> > Enrico
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> >
> > > > >> > >
> > > > >> > > Patrick
> > > > >> > >
> > > > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> > > > eolivelli@gmail.com>
> > > > >> > > wrote:
> > > > >> > >
> > > > >> > > > Thank you Edward
> > > > >> > > >
> > > > >> > > > I will pack all together and send out a patch as soon as I
> > have
> > > > >> time.
> > > > >> > > > I am running 3.5 in production and given than an RC for
> 3.5.4
> > is
> > > > >> going
> > > > >> > to
> > > > >> > > > be cut soon I will have to wait for 3.5.5 and I assume it
> > won't
> > > be
> > > > >> > > > immediate.
> > > > >> > > >
> > > > >> > > > Cheers
> > > > >> > > > Enrico
> > > > >> > > >
> > > > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > > >> > > > edward.ribeiro@gmail.com> ha scritto:
> > > > >> > > >
> > > > >> > > > > Sent before finishing the previous email. Only to
> > complement,
> > > > the
> > > > >> > > > > findLeader() could have been as below, but this change is
> > > only a
> > > > >> > nitty
> > > > >> > > > > detail and totally irrelevant to the questions you are
> > asking.
> > > > :)
> > > > >> > > > >
> > > > >> > > > > /**
> > > > >> > > > > * Returns the address of the node we think is the leader.
> > > > >> > > > > */
> > > > >> > > > > protected QuorumServer findLeader() {
> > > > >> > > > >
> > > > >> > > > > // Find the leader by id
> > > > >> > > > > long currentLeader = self.getCurrentVote().getId();
> > > > >> > > > >
> > > > >> > > > > QuorumServer leaderServer =
> > > > self.getView().get(currentLeader);
> > > > >> > > > >
> > > > >> > > > > if (leaderServer == null) {
> > > > >> > > > > LOG.warn("Couldn't find the leader with id = {}",
> > > > >> > > currentLeader);
> > > > >> > > > > }
> > > > >> > > > > return leaderServer;
> > > > >> > > > > }
> > > > >> > > > >
> > > > >> > > > > Edward
> > > > >> > > > >
> > > > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > > > >> > > edward.ribeiro@gmail.com
> > > > >> > > > >
> > > > >> > > > > wrote:
> > > > >> > > > >
> > > > >> > > > > > Hi Enrico,
> > > > >> > > > > >
> > > > >> > > > > > Well, I am not an expert on QuorumPeer either (not an
> > expert
> > > > on
> > > > >> > > > anything,
> > > > >> > > > > > really), but maybe it's the variable and method below?
> > > > >> > > > > >
> > > > >> > > > > > ----------------- QuorumPeer ------------------
> > > > >> > > > > >
> > > > >> > > > > > /**
> > > > >> > > > > > * This is who I think the leader currently is.
> > > > >> > > > > > */
> > > > >> > > > > > volatile private Vote currentVote;
> > > > >> > > > > >
> > > > >> > > > > > public synchronized Vote getCurrentVote(){
> > > > >> > > > > > return currentVote;
> > > > >> > > > > > }
> > > > >> > > > > >
> > > > >> > > > > > ---------------------------------------
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > > > Then it's a matter of calling
> > > > >> quorumPeer.getCurrentVote().getId()
> > > > >> > and
> > > > >> > > > > > quorumPeer.getServerState()?
> > > > >> > > > > >
> > > > >> > > > > > Btw, the Learner class has this handy method below (self
> > is
> > > a
> > > > >> > > > > QuorumPeer):
> > > > >> > > > > >
> > > > >> > > > > > ---------------- Learner --------------------
> > > > >> > > > > >
> > > > >> > > > > > /**
> > > > >> > > > > > * Returns the address of the node we think is the
> leader.
> > > > >> > > > > > */
> > > > >> > > > > > protected QuorumServer findLeader() {
> > > > >> > > > > > QuorumServer leaderServer = null;
> > > > >> > > > > > // Find the leader by id
> > > > >> > > > > > Vote current = self.getCurrentVote();
> > > > >> > > > > > for (QuorumServer s : self.getView().values()) {
> > > > >> > > > > > if (s.id == current.getId()) {
> > > > >> > > > > > leaderServer = s;
> > > > >> > > > > > break;
> > > > >> > > > > > }
> > > > >> > > > > > }
> > > > >> > > > > > if (leaderServer == null) {
> > > > >> > > > > > LOG.warn("Couldn't find the leader with id = "
> > > > >> > > > > > + current.getId());
> > > > >> > > > > > }
> > > > >> > > > > > return leaderServer;
> > > > >> > > > > > }
> > > > >> > > > > >
> > > > >> > > > > > ---------------------------------------
> > > > >> > > > > >
> > > > >> > > > > > By the way, as a side note, the map traversal could be
> > > changed
> > > > >> by:
> > > > >> > > > > >
> > > > >> > > > > > ----------------------------
> > > > >> > > > > >
> > > > >> > > > > > if (self.getView().contains(current.getId()) {
> > > > >> > > > > >
> > > > >> > > > > > }
> > > > >> > > > > >
> > > > >> > > > > > ---------------------------
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > > > You can see above this method the quorumPeer.getView()
> > > > returns a
> > > > >> > > > Map<sid,
> > > > >> > > > > > QuorumServer> as below:
> > > > >> > > > > >
> > > > >> > > > > > -------------QuorumPeer ---------
> > > > >> > > > > >
> > > > >> > > > > > /**
> > > > >> > > > > > * A 'view' is a node's current opinion of the
> membership
> > of
> > > > the
> > > > >> > > entire
> > > > >> > > > > > * ensemble.
> > > > >> > > > > > */
> > > > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > >> > > > > > return Collections.unmodifiableMap(
> > getQuorumVerifier().
> > > > >> > > > > > getAllMembers());
> > > > >> > > > > > }
> > > > >> > > > > >
> > > > >> > > > > > -----------------------------
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > > > And then it retrieves the QuorumServer that has many
> more
> > > > >> > information
> > > > >> > > > > > about the node besides the sid (InetSocketAddress,
> > hostname,
> > > > >> etc).
> > > > >> > :)
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > > > Cheers,
> > > > >> > > > > > Edward
> > > > >> > > > > >
> > > > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > > > >> > eolivelli@gmail.com
> > > > >> > > >
> > > > >> > > > > > wrote:
> > > > >> > > > > >
> > > > >> > > > > >> So I am trying to create a patch in order to expose on
> > JMX
> > > > the
> > > > >> id
> > > > >> > of
> > > > >> > > > the
> > > > >> > > > > >> current "leader" (on the JVM of a follower)
> > > > >> > > > > >>
> > > > >> > > > > >> I am trying to find in ZK which is the variable which
> > holds
> > > > >> the ID
> > > > >> > > of
> > > > >> > > > > the
> > > > >> > > > > >> current leader.
> > > > >> > > > > >> I am new to the internal of QuorumPeer
> > > > >> > > > > >>
> > > > >> > > > > >> Can someone give me some hint ?
> > > > >> > > > > >>
> > > > >> > > > > >> Enrico
> > > > >> > > > > >>
> > > > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel
> Zandegran <
> > > > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > >> > > > > >>
> > > > >> > > > > >> > Hi,
> > > > >> > > > > >> > That is possible with 4 letter commands. We are using
> > it
> > > > >> now. In
> > > > >> > > > 3.5.x
> > > > >> > > > > >> it
> > > > >> > > > > >> > is going to be removed in favour of admin server
> > > (embedded
> > > > >> web
> > > > >> > > > > server).
> > > > >> > > > > >> > We are running in an environment where it’s not
> > possible
> > > to
> > > > >> run
> > > > >> > > JMX
> > > > >> > > > or
> > > > >> > > > > >> > embedded web servers.
> > > > >> > > > > >> >
> > > > >> > > > > >> > So I am wondering if there is another way? It would
> be
> > > nice
> > > > >> to
> > > > >> > > have
> > > > >> > > > > this
> > > > >> > > > > >> > info as a znode.
> > > > >> > > > > >> >
> > > > >> > > > > >> > Best regards,
> > > > >> > > > > >> > Ansel
> > > > >> > > > > >> >
> > > > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> > > > fpj@apache.org>
> > > > >> > > wrote:
> > > > >> > > > > >> > >
> > > > >> > > > > >> > > Hi Enrico,
> > > > >> > > > > >> > >
> > > > >> > > > > >> > > You can determine the state of a server it via
> > 4-letter
> > > > >> > > commands.
> > > > >> > > > > >> Would
> > > > >> > > > > >> > that work for you?
> > > > >> > > > > >> > >
> > > > >> > > > > >> > > -Flavio
> > > > >> > > > > >> > >
> > > > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > > > >> > eolivelli@gmail.com>
> > > > >> > > > > >> wrote:
> > > > >> > > > > >> > >>
> > > > >> > > > > >> > >> Hi,
> > > > >> > > > > >> > >> is there any way to see in JMX which is the leader
> > of
> > > a
> > > > >> > > ZooKeeper
> > > > >> > > > > >> > cluster?
> > > > >> > > > > >> > >>
> > > > >> > > > > >> > >> My problem is: given access to any of the nodes of
> > the
> > > > >> > cluster
> > > > >> > > I
> > > > >> > > > > >> want to
> > > > >> > > > > >> > >> know from JMX which is the current leader.
> > > > >> > > > > >> > >> It seems to me that this information is not
> > available,
> > > > you
> > > > >> > can
> > > > >> > > > know
> > > > >> > > > > >> > only if
> > > > >> > > > > >> > >> the local node is Leader or Follower.
> > > > >> > > > > >> > >>
> > > > >> > > > > >> > >> Cheers
> > > > >> > > > > >> > >> Enrico
> > > > >> > > > > >> > >
> > > > >> > > > > >> >
> > > > >> > > > > >> >
> > > > >> > > > > >>
> > > > >> > > > > >
> > > > >> > > > > >
> > > > >> > > > >
> > > > >> > > >
> > > > >> > >
> > > > >> >
> > > > >>
> > > > > --
> > > > >
> > > > >
> > > > > -- Enrico Olivelli
> > > > >
> > > >
> > >
> >
>
--
-- Enrico Olivelli
Re: Discover LEADER from JMX
Posted by Andor Molnar <an...@cloudera.com.INVALID>.
Hi Enrico!
Take a look at testElectionFraud(), it might be useful to you.
Regards,
Andor
On Thu, Jun 21, 2018 at 12:00 PM, Enrico Olivelli <eo...@gmail.com>
wrote:
> Norbert,
> thank you for taking a look
>
> Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
> <nk...@cloudera.com.invalid> ha scritto:
>
> > Good question. Wouldn't just killing the leader do the job?
> >
>
> It seems to me that is it not "immediate" to "kill" a QuorumPeer inside
> such test.
> If you "shutdown" it you cannot 'start' it anymore.
>
> This is why I am asking for help.
>
> -- Enrico
>
>
>
> >
> > Regards,
> > Norbert
> >
> > On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <eo...@gmail.com>
> > wrote:
> >
> > > This is my patch
> > > https://github.com/apache/zookeeper/pull/546
> > >
> > > One question:
> > > I would like to force the cluster to change leader in
> > > HierarchicalQuorumTest, so that I can test that JMX will reflect the
> new
> > > status of the group.
> > > Any idea about how to bounce the leader ?
> > >
> > > Cheers
> > > Enrico
> > >
> > > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> > > eolivelli@gmail.com> ha scritto:
> > >
> > > > This is my JIRA
> > > > I am going to work on a patch
> > > >
> > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> > > >
> > > > Enrico
> > > >
> > > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha
> > scritto:
> > > >
> > > >> "in order to guess which is the leader I have to ask to all of the
> > three
> > > >> nodes in the cluster"
> > > >>
> > > >> That's correct.
> > > >>
> > > >> Regards,
> > > >> Andor
> > > >>
> > > >>
> > > >>
> > > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <
> eolivelli@gmail.com
> > >
> > > >> wrote:
> > > >>
> > > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> > > phunt@apache.org>
> > > >> ha
> > > >> > scritto:
> > > >> >
> > > >> > > iiuc what you are interested in the information is already
> > > available.
> > > >> The
> > > >> > > beans have a "state" attribute which indicates following vs
> > leading.
> > > >> > >
> > > >> > > Try attaching a jconsole to the running servers, use the
> "mbeans"
> > > tab
> > > >> and
> > > >> > > open org.apache.ZooKeeperService -> replicatedserver -> replica
> ->
> > > >> > > attributes, you'll see the "state" attribute there.
> > > >> > >
> > > >> >
> > > >> >
> > > >> > Patrick,
> > > >> > I can't find this information.
> > > >> > If I log into a "follower" I get this info only for the 'current
> > > >> replica'
> > > >> >
> > > >> > Example, I have three peers, the first one is a "Follower", on
> JMX
> > I
> > > >> have
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > ClientAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > >> ElectionAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > LearnerType
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > QuorumAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> > > >> > following
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > > ConfigVersion
> > > >> > .....
> > > >> >
> > > >> >
> > > >> >
> > > >> > for other peers I see only
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > ClientAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > >> ElectionAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > LearnerType
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > > QuorumAddress
> > > >> >
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > ClientAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > >> ElectionAddress
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > LearnerType
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> > > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > > QuorumAddress
> > > >> >
> > > >> >
> > > >> > so quering only this server I cannot guess which is the current
> > > leader,
> > > >> the
> > > >> > only information I can extract is:
> > > >> > - I am a follower
> > > >> > - We are a cluster of three
> > > >> > - Every of the three is a PARTECIPANT (no observers)
> > > >> >
> > > >> > in order to guess which is the leader I have to ask to all of the
> > > three
> > > >> > nodes in the cluster
> > > >> >
> > > >> > Am I missing something ? I am running 3.5.3-BETA
> > > >> >
> > > >> > Enrico
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> > >
> > > >> > > Patrick
> > > >> > >
> > > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> > > eolivelli@gmail.com>
> > > >> > > wrote:
> > > >> > >
> > > >> > > > Thank you Edward
> > > >> > > >
> > > >> > > > I will pack all together and send out a patch as soon as I
> have
> > > >> time.
> > > >> > > > I am running 3.5 in production and given than an RC for 3.5.4
> is
> > > >> going
> > > >> > to
> > > >> > > > be cut soon I will have to wait for 3.5.5 and I assume it
> won't
> > be
> > > >> > > > immediate.
> > > >> > > >
> > > >> > > > Cheers
> > > >> > > > Enrico
> > > >> > > >
> > > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > >> > > > edward.ribeiro@gmail.com> ha scritto:
> > > >> > > >
> > > >> > > > > Sent before finishing the previous email. Only to
> complement,
> > > the
> > > >> > > > > findLeader() could have been as below, but this change is
> > only a
> > > >> > nitty
> > > >> > > > > detail and totally irrelevant to the questions you are
> asking.
> > > :)
> > > >> > > > >
> > > >> > > > > /**
> > > >> > > > > * Returns the address of the node we think is the leader.
> > > >> > > > > */
> > > >> > > > > protected QuorumServer findLeader() {
> > > >> > > > >
> > > >> > > > > // Find the leader by id
> > > >> > > > > long currentLeader = self.getCurrentVote().getId();
> > > >> > > > >
> > > >> > > > > QuorumServer leaderServer =
> > > self.getView().get(currentLeader);
> > > >> > > > >
> > > >> > > > > if (leaderServer == null) {
> > > >> > > > > LOG.warn("Couldn't find the leader with id = {}",
> > > >> > > currentLeader);
> > > >> > > > > }
> > > >> > > > > return leaderServer;
> > > >> > > > > }
> > > >> > > > >
> > > >> > > > > Edward
> > > >> > > > >
> > > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > > >> > > edward.ribeiro@gmail.com
> > > >> > > > >
> > > >> > > > > wrote:
> > > >> > > > >
> > > >> > > > > > Hi Enrico,
> > > >> > > > > >
> > > >> > > > > > Well, I am not an expert on QuorumPeer either (not an
> expert
> > > on
> > > >> > > > anything,
> > > >> > > > > > really), but maybe it's the variable and method below?
> > > >> > > > > >
> > > >> > > > > > ----------------- QuorumPeer ------------------
> > > >> > > > > >
> > > >> > > > > > /**
> > > >> > > > > > * This is who I think the leader currently is.
> > > >> > > > > > */
> > > >> > > > > > volatile private Vote currentVote;
> > > >> > > > > >
> > > >> > > > > > public synchronized Vote getCurrentVote(){
> > > >> > > > > > return currentVote;
> > > >> > > > > > }
> > > >> > > > > >
> > > >> > > > > > ---------------------------------------
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > > > Then it's a matter of calling
> > > >> quorumPeer.getCurrentVote().getId()
> > > >> > and
> > > >> > > > > > quorumPeer.getServerState()?
> > > >> > > > > >
> > > >> > > > > > Btw, the Learner class has this handy method below (self
> is
> > a
> > > >> > > > > QuorumPeer):
> > > >> > > > > >
> > > >> > > > > > ---------------- Learner --------------------
> > > >> > > > > >
> > > >> > > > > > /**
> > > >> > > > > > * Returns the address of the node we think is the leader.
> > > >> > > > > > */
> > > >> > > > > > protected QuorumServer findLeader() {
> > > >> > > > > > QuorumServer leaderServer = null;
> > > >> > > > > > // Find the leader by id
> > > >> > > > > > Vote current = self.getCurrentVote();
> > > >> > > > > > for (QuorumServer s : self.getView().values()) {
> > > >> > > > > > if (s.id == current.getId()) {
> > > >> > > > > > leaderServer = s;
> > > >> > > > > > break;
> > > >> > > > > > }
> > > >> > > > > > }
> > > >> > > > > > if (leaderServer == null) {
> > > >> > > > > > LOG.warn("Couldn't find the leader with id = "
> > > >> > > > > > + current.getId());
> > > >> > > > > > }
> > > >> > > > > > return leaderServer;
> > > >> > > > > > }
> > > >> > > > > >
> > > >> > > > > > ---------------------------------------
> > > >> > > > > >
> > > >> > > > > > By the way, as a side note, the map traversal could be
> > changed
> > > >> by:
> > > >> > > > > >
> > > >> > > > > > ----------------------------
> > > >> > > > > >
> > > >> > > > > > if (self.getView().contains(current.getId()) {
> > > >> > > > > >
> > > >> > > > > > }
> > > >> > > > > >
> > > >> > > > > > ---------------------------
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > > > You can see above this method the quorumPeer.getView()
> > > returns a
> > > >> > > > Map<sid,
> > > >> > > > > > QuorumServer> as below:
> > > >> > > > > >
> > > >> > > > > > -------------QuorumPeer ---------
> > > >> > > > > >
> > > >> > > > > > /**
> > > >> > > > > > * A 'view' is a node's current opinion of the membership
> of
> > > the
> > > >> > > entire
> > > >> > > > > > * ensemble.
> > > >> > > > > > */
> > > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > >> > > > > > return Collections.unmodifiableMap(
> getQuorumVerifier().
> > > >> > > > > > getAllMembers());
> > > >> > > > > > }
> > > >> > > > > >
> > > >> > > > > > -----------------------------
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > > > And then it retrieves the QuorumServer that has many more
> > > >> > information
> > > >> > > > > > about the node besides the sid (InetSocketAddress,
> hostname,
> > > >> etc).
> > > >> > :)
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > > > Cheers,
> > > >> > > > > > Edward
> > > >> > > > > >
> > > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > > >> > eolivelli@gmail.com
> > > >> > > >
> > > >> > > > > > wrote:
> > > >> > > > > >
> > > >> > > > > >> So I am trying to create a patch in order to expose on
> JMX
> > > the
> > > >> id
> > > >> > of
> > > >> > > > the
> > > >> > > > > >> current "leader" (on the JVM of a follower)
> > > >> > > > > >>
> > > >> > > > > >> I am trying to find in ZK which is the variable which
> holds
> > > >> the ID
> > > >> > > of
> > > >> > > > > the
> > > >> > > > > >> current leader.
> > > >> > > > > >> I am new to the internal of QuorumPeer
> > > >> > > > > >>
> > > >> > > > > >> Can someone give me some hint ?
> > > >> > > > > >>
> > > >> > > > > >> Enrico
> > > >> > > > > >>
> > > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > >> > > > > >>
> > > >> > > > > >> > Hi,
> > > >> > > > > >> > That is possible with 4 letter commands. We are using
> it
> > > >> now. In
> > > >> > > > 3.5.x
> > > >> > > > > >> it
> > > >> > > > > >> > is going to be removed in favour of admin server
> > (embedded
> > > >> web
> > > >> > > > > server).
> > > >> > > > > >> > We are running in an environment where it’s not
> possible
> > to
> > > >> run
> > > >> > > JMX
> > > >> > > > or
> > > >> > > > > >> > embedded web servers.
> > > >> > > > > >> >
> > > >> > > > > >> > So I am wondering if there is another way? It would be
> > nice
> > > >> to
> > > >> > > have
> > > >> > > > > this
> > > >> > > > > >> > info as a znode.
> > > >> > > > > >> >
> > > >> > > > > >> > Best regards,
> > > >> > > > > >> > Ansel
> > > >> > > > > >> >
> > > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> > > fpj@apache.org>
> > > >> > > wrote:
> > > >> > > > > >> > >
> > > >> > > > > >> > > Hi Enrico,
> > > >> > > > > >> > >
> > > >> > > > > >> > > You can determine the state of a server it via
> 4-letter
> > > >> > > commands.
> > > >> > > > > >> Would
> > > >> > > > > >> > that work for you?
> > > >> > > > > >> > >
> > > >> > > > > >> > > -Flavio
> > > >> > > > > >> > >
> > > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > > >> > eolivelli@gmail.com>
> > > >> > > > > >> wrote:
> > > >> > > > > >> > >>
> > > >> > > > > >> > >> Hi,
> > > >> > > > > >> > >> is there any way to see in JMX which is the leader
> of
> > a
> > > >> > > ZooKeeper
> > > >> > > > > >> > cluster?
> > > >> > > > > >> > >>
> > > >> > > > > >> > >> My problem is: given access to any of the nodes of
> the
> > > >> > cluster
> > > >> > > I
> > > >> > > > > >> want to
> > > >> > > > > >> > >> know from JMX which is the current leader.
> > > >> > > > > >> > >> It seems to me that this information is not
> available,
> > > you
> > > >> > can
> > > >> > > > know
> > > >> > > > > >> > only if
> > > >> > > > > >> > >> the local node is Leader or Follower.
> > > >> > > > > >> > >>
> > > >> > > > > >> > >> Cheers
> > > >> > > > > >> > >> Enrico
> > > >> > > > > >> > >
> > > >> > > > > >> >
> > > >> > > > > >> >
> > > >> > > > > >>
> > > >> > > > > >
> > > >> > > > > >
> > > >> > > > >
> > > >> > > >
> > > >> > >
> > > >> >
> > > >>
> > > > --
> > > >
> > > >
> > > > -- Enrico Olivelli
> > > >
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Norbert,
thank you for taking a look
Il giorno gio 21 giu 2018 alle ore 11:58 Norbert Kalmar
<nk...@cloudera.com.invalid> ha scritto:
> Good question. Wouldn't just killing the leader do the job?
>
It seems to me that is it not "immediate" to "kill" a QuorumPeer inside
such test.
If you "shutdown" it you cannot 'start' it anymore.
This is why I am asking for help.
-- Enrico
>
> Regards,
> Norbert
>
> On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <eo...@gmail.com>
> wrote:
>
> > This is my patch
> > https://github.com/apache/zookeeper/pull/546
> >
> > One question:
> > I would like to force the cluster to change leader in
> > HierarchicalQuorumTest, so that I can test that JMX will reflect the new
> > status of the group.
> > Any idea about how to bounce the leader ?
> >
> > Cheers
> > Enrico
> >
> > Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> > eolivelli@gmail.com> ha scritto:
> >
> > > This is my JIRA
> > > I am going to work on a patch
> > >
> > > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> > >
> > > Enrico
> > >
> > > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha
> scritto:
> > >
> > >> "in order to guess which is the leader I have to ask to all of the
> three
> > >> nodes in the cluster"
> > >>
> > >> That's correct.
> > >>
> > >> Regards,
> > >> Andor
> > >>
> > >>
> > >>
> > >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eolivelli@gmail.com
> >
> > >> wrote:
> > >>
> > >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> > phunt@apache.org>
> > >> ha
> > >> > scritto:
> > >> >
> > >> > > iiuc what you are interested in the information is already
> > available.
> > >> The
> > >> > > beans have a "state" attribute which indicates following vs
> leading.
> > >> > >
> > >> > > Try attaching a jconsole to the running servers, use the "mbeans"
> > tab
> > >> and
> > >> > > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> > >> > > attributes, you'll see the "state" attribute there.
> > >> > >
> > >> >
> > >> >
> > >> > Patrick,
> > >> > I can't find this information.
> > >> > If I log into a "follower" I get this info only for the 'current
> > >> replica'
> > >> >
> > >> > Example, I have three peers, the first one is a "Follower", on JMX
> I
> > >> have
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > ClientAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > >> ElectionAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> LearnerType
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > QuorumAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> > >> > following
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> > ConfigVersion
> > >> > .....
> > >> >
> > >> >
> > >> >
> > >> > for other peers I see only
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > ClientAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > >> ElectionAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> LearnerType
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> > QuorumAddress
> > >> >
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > ClientAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > >> ElectionAddress
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> LearnerType
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> > >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> > QuorumAddress
> > >> >
> > >> >
> > >> > so quering only this server I cannot guess which is the current
> > leader,
> > >> the
> > >> > only information I can extract is:
> > >> > - I am a follower
> > >> > - We are a cluster of three
> > >> > - Every of the three is a PARTECIPANT (no observers)
> > >> >
> > >> > in order to guess which is the leader I have to ask to all of the
> > three
> > >> > nodes in the cluster
> > >> >
> > >> > Am I missing something ? I am running 3.5.3-BETA
> > >> >
> > >> > Enrico
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> > >
> > >> > > Patrick
> > >> > >
> > >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> > eolivelli@gmail.com>
> > >> > > wrote:
> > >> > >
> > >> > > > Thank you Edward
> > >> > > >
> > >> > > > I will pack all together and send out a patch as soon as I have
> > >> time.
> > >> > > > I am running 3.5 in production and given than an RC for 3.5.4 is
> > >> going
> > >> > to
> > >> > > > be cut soon I will have to wait for 3.5.5 and I assume it won't
> be
> > >> > > > immediate.
> > >> > > >
> > >> > > > Cheers
> > >> > > > Enrico
> > >> > > >
> > >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > >> > > > edward.ribeiro@gmail.com> ha scritto:
> > >> > > >
> > >> > > > > Sent before finishing the previous email. Only to complement,
> > the
> > >> > > > > findLeader() could have been as below, but this change is
> only a
> > >> > nitty
> > >> > > > > detail and totally irrelevant to the questions you are asking.
> > :)
> > >> > > > >
> > >> > > > > /**
> > >> > > > > * Returns the address of the node we think is the leader.
> > >> > > > > */
> > >> > > > > protected QuorumServer findLeader() {
> > >> > > > >
> > >> > > > > // Find the leader by id
> > >> > > > > long currentLeader = self.getCurrentVote().getId();
> > >> > > > >
> > >> > > > > QuorumServer leaderServer =
> > self.getView().get(currentLeader);
> > >> > > > >
> > >> > > > > if (leaderServer == null) {
> > >> > > > > LOG.warn("Couldn't find the leader with id = {}",
> > >> > > currentLeader);
> > >> > > > > }
> > >> > > > > return leaderServer;
> > >> > > > > }
> > >> > > > >
> > >> > > > > Edward
> > >> > > > >
> > >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > >> > > edward.ribeiro@gmail.com
> > >> > > > >
> > >> > > > > wrote:
> > >> > > > >
> > >> > > > > > Hi Enrico,
> > >> > > > > >
> > >> > > > > > Well, I am not an expert on QuorumPeer either (not an expert
> > on
> > >> > > > anything,
> > >> > > > > > really), but maybe it's the variable and method below?
> > >> > > > > >
> > >> > > > > > ----------------- QuorumPeer ------------------
> > >> > > > > >
> > >> > > > > > /**
> > >> > > > > > * This is who I think the leader currently is.
> > >> > > > > > */
> > >> > > > > > volatile private Vote currentVote;
> > >> > > > > >
> > >> > > > > > public synchronized Vote getCurrentVote(){
> > >> > > > > > return currentVote;
> > >> > > > > > }
> > >> > > > > >
> > >> > > > > > ---------------------------------------
> > >> > > > > >
> > >> > > > > >
> > >> > > > > > Then it's a matter of calling
> > >> quorumPeer.getCurrentVote().getId()
> > >> > and
> > >> > > > > > quorumPeer.getServerState()?
> > >> > > > > >
> > >> > > > > > Btw, the Learner class has this handy method below (self is
> a
> > >> > > > > QuorumPeer):
> > >> > > > > >
> > >> > > > > > ---------------- Learner --------------------
> > >> > > > > >
> > >> > > > > > /**
> > >> > > > > > * Returns the address of the node we think is the leader.
> > >> > > > > > */
> > >> > > > > > protected QuorumServer findLeader() {
> > >> > > > > > QuorumServer leaderServer = null;
> > >> > > > > > // Find the leader by id
> > >> > > > > > Vote current = self.getCurrentVote();
> > >> > > > > > for (QuorumServer s : self.getView().values()) {
> > >> > > > > > if (s.id == current.getId()) {
> > >> > > > > > leaderServer = s;
> > >> > > > > > break;
> > >> > > > > > }
> > >> > > > > > }
> > >> > > > > > if (leaderServer == null) {
> > >> > > > > > LOG.warn("Couldn't find the leader with id = "
> > >> > > > > > + current.getId());
> > >> > > > > > }
> > >> > > > > > return leaderServer;
> > >> > > > > > }
> > >> > > > > >
> > >> > > > > > ---------------------------------------
> > >> > > > > >
> > >> > > > > > By the way, as a side note, the map traversal could be
> changed
> > >> by:
> > >> > > > > >
> > >> > > > > > ----------------------------
> > >> > > > > >
> > >> > > > > > if (self.getView().contains(current.getId()) {
> > >> > > > > >
> > >> > > > > > }
> > >> > > > > >
> > >> > > > > > ---------------------------
> > >> > > > > >
> > >> > > > > >
> > >> > > > > >
> > >> > > > > > You can see above this method the quorumPeer.getView()
> > returns a
> > >> > > > Map<sid,
> > >> > > > > > QuorumServer> as below:
> > >> > > > > >
> > >> > > > > > -------------QuorumPeer ---------
> > >> > > > > >
> > >> > > > > > /**
> > >> > > > > > * A 'view' is a node's current opinion of the membership of
> > the
> > >> > > entire
> > >> > > > > > * ensemble.
> > >> > > > > > */
> > >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > >> > > > > > return Collections.unmodifiableMap(getQuorumVerifier().
> > >> > > > > > getAllMembers());
> > >> > > > > > }
> > >> > > > > >
> > >> > > > > > -----------------------------
> > >> > > > > >
> > >> > > > > >
> > >> > > > > > And then it retrieves the QuorumServer that has many more
> > >> > information
> > >> > > > > > about the node besides the sid (InetSocketAddress, hostname,
> > >> etc).
> > >> > :)
> > >> > > > > >
> > >> > > > > >
> > >> > > > > > Cheers,
> > >> > > > > > Edward
> > >> > > > > >
> > >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > >> > eolivelli@gmail.com
> > >> > > >
> > >> > > > > > wrote:
> > >> > > > > >
> > >> > > > > >> So I am trying to create a patch in order to expose on JMX
> > the
> > >> id
> > >> > of
> > >> > > > the
> > >> > > > > >> current "leader" (on the JVM of a follower)
> > >> > > > > >>
> > >> > > > > >> I am trying to find in ZK which is the variable which holds
> > >> the ID
> > >> > > of
> > >> > > > > the
> > >> > > > > >> current leader.
> > >> > > > > >> I am new to the internal of QuorumPeer
> > >> > > > > >>
> > >> > > > > >> Can someone give me some hint ?
> > >> > > > > >>
> > >> > > > > >> Enrico
> > >> > > > > >>
> > >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > >> > > > > >>
> > >> > > > > >> > Hi,
> > >> > > > > >> > That is possible with 4 letter commands. We are using it
> > >> now. In
> > >> > > > 3.5.x
> > >> > > > > >> it
> > >> > > > > >> > is going to be removed in favour of admin server
> (embedded
> > >> web
> > >> > > > > server).
> > >> > > > > >> > We are running in an environment where it’s not possible
> to
> > >> run
> > >> > > JMX
> > >> > > > or
> > >> > > > > >> > embedded web servers.
> > >> > > > > >> >
> > >> > > > > >> > So I am wondering if there is another way? It would be
> nice
> > >> to
> > >> > > have
> > >> > > > > this
> > >> > > > > >> > info as a znode.
> > >> > > > > >> >
> > >> > > > > >> > Best regards,
> > >> > > > > >> > Ansel
> > >> > > > > >> >
> > >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> > fpj@apache.org>
> > >> > > wrote:
> > >> > > > > >> > >
> > >> > > > > >> > > Hi Enrico,
> > >> > > > > >> > >
> > >> > > > > >> > > You can determine the state of a server it via 4-letter
> > >> > > commands.
> > >> > > > > >> Would
> > >> > > > > >> > that work for you?
> > >> > > > > >> > >
> > >> > > > > >> > > -Flavio
> > >> > > > > >> > >
> > >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > >> > eolivelli@gmail.com>
> > >> > > > > >> wrote:
> > >> > > > > >> > >>
> > >> > > > > >> > >> Hi,
> > >> > > > > >> > >> is there any way to see in JMX which is the leader of
> a
> > >> > > ZooKeeper
> > >> > > > > >> > cluster?
> > >> > > > > >> > >>
> > >> > > > > >> > >> My problem is: given access to any of the nodes of the
> > >> > cluster
> > >> > > I
> > >> > > > > >> want to
> > >> > > > > >> > >> know from JMX which is the current leader.
> > >> > > > > >> > >> It seems to me that this information is not available,
> > you
> > >> > can
> > >> > > > know
> > >> > > > > >> > only if
> > >> > > > > >> > >> the local node is Leader or Follower.
> > >> > > > > >> > >>
> > >> > > > > >> > >> Cheers
> > >> > > > > >> > >> Enrico
> > >> > > > > >> > >
> > >> > > > > >> >
> > >> > > > > >> >
> > >> > > > > >>
> > >> > > > > >
> > >> > > > > >
> > >> > > > >
> > >> > > >
> > >> > >
> > >> >
> > >>
> > > --
> > >
> > >
> > > -- Enrico Olivelli
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Norbert Kalmar <nk...@cloudera.com.INVALID>.
Good question. Wouldn't just killing the leader do the job?
Regards,
Norbert
On Thu, Jun 21, 2018 at 3:51 AM Enrico Olivelli <eo...@gmail.com> wrote:
> This is my patch
> https://github.com/apache/zookeeper/pull/546
>
> One question:
> I would like to force the cluster to change leader in
> HierarchicalQuorumTest, so that I can test that JMX will reflect the new
> status of the group.
> Any idea about how to bounce the leader ?
>
> Cheers
> Enrico
>
> Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
> eolivelli@gmail.com> ha scritto:
>
> > This is my JIRA
> > I am going to work on a patch
> >
> > https://issues.apache.org/jira/browse/ZOOKEEPER-3066
> >
> > Enrico
> >
> > Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha scritto:
> >
> >> "in order to guess which is the leader I have to ask to all of the three
> >> nodes in the cluster"
> >>
> >> That's correct.
> >>
> >> Regards,
> >> Andor
> >>
> >>
> >>
> >> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eo...@gmail.com>
> >> wrote:
> >>
> >> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <
> phunt@apache.org>
> >> ha
> >> > scritto:
> >> >
> >> > > iiuc what you are interested in the information is already
> available.
> >> The
> >> > > beans have a "state" attribute which indicates following vs leading.
> >> > >
> >> > > Try attaching a jconsole to the running servers, use the "mbeans"
> tab
> >> and
> >> > > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> >> > > attributes, you'll see the "state" attribute there.
> >> > >
> >> >
> >> >
> >> > Patrick,
> >> > I can't find this information.
> >> > If I log into a "follower" I get this info only for the 'current
> >> replica'
> >> >
> >> > Example, I have three peers, the first one is a "Follower", on JMX I
> >> have
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> ClientAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> >> ElectionAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> QuorumAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> >> > following
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> ConfigVersion
> >> > .....
> >> >
> >> >
> >> >
> >> > for other peers I see only
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> ClientAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> >> ElectionAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> QuorumAddress
> >> >
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> ClientAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> >> ElectionAddress
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> >> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> QuorumAddress
> >> >
> >> >
> >> > so quering only this server I cannot guess which is the current
> leader,
> >> the
> >> > only information I can extract is:
> >> > - I am a follower
> >> > - We are a cluster of three
> >> > - Every of the three is a PARTECIPANT (no observers)
> >> >
> >> > in order to guess which is the leader I have to ask to all of the
> three
> >> > nodes in the cluster
> >> >
> >> > Am I missing something ? I am running 3.5.3-BETA
> >> >
> >> > Enrico
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > >
> >> > > Patrick
> >> > >
> >> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <
> eolivelli@gmail.com>
> >> > > wrote:
> >> > >
> >> > > > Thank you Edward
> >> > > >
> >> > > > I will pack all together and send out a patch as soon as I have
> >> time.
> >> > > > I am running 3.5 in production and given than an RC for 3.5.4 is
> >> going
> >> > to
> >> > > > be cut soon I will have to wait for 3.5.5 and I assume it won't be
> >> > > > immediate.
> >> > > >
> >> > > > Cheers
> >> > > > Enrico
> >> > > >
> >> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> >> > > > edward.ribeiro@gmail.com> ha scritto:
> >> > > >
> >> > > > > Sent before finishing the previous email. Only to complement,
> the
> >> > > > > findLeader() could have been as below, but this change is only a
> >> > nitty
> >> > > > > detail and totally irrelevant to the questions you are asking.
> :)
> >> > > > >
> >> > > > > /**
> >> > > > > * Returns the address of the node we think is the leader.
> >> > > > > */
> >> > > > > protected QuorumServer findLeader() {
> >> > > > >
> >> > > > > // Find the leader by id
> >> > > > > long currentLeader = self.getCurrentVote().getId();
> >> > > > >
> >> > > > > QuorumServer leaderServer =
> self.getView().get(currentLeader);
> >> > > > >
> >> > > > > if (leaderServer == null) {
> >> > > > > LOG.warn("Couldn't find the leader with id = {}",
> >> > > currentLeader);
> >> > > > > }
> >> > > > > return leaderServer;
> >> > > > > }
> >> > > > >
> >> > > > > Edward
> >> > > > >
> >> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> >> > > edward.ribeiro@gmail.com
> >> > > > >
> >> > > > > wrote:
> >> > > > >
> >> > > > > > Hi Enrico,
> >> > > > > >
> >> > > > > > Well, I am not an expert on QuorumPeer either (not an expert
> on
> >> > > > anything,
> >> > > > > > really), but maybe it's the variable and method below?
> >> > > > > >
> >> > > > > > ----------------- QuorumPeer ------------------
> >> > > > > >
> >> > > > > > /**
> >> > > > > > * This is who I think the leader currently is.
> >> > > > > > */
> >> > > > > > volatile private Vote currentVote;
> >> > > > > >
> >> > > > > > public synchronized Vote getCurrentVote(){
> >> > > > > > return currentVote;
> >> > > > > > }
> >> > > > > >
> >> > > > > > ---------------------------------------
> >> > > > > >
> >> > > > > >
> >> > > > > > Then it's a matter of calling
> >> quorumPeer.getCurrentVote().getId()
> >> > and
> >> > > > > > quorumPeer.getServerState()?
> >> > > > > >
> >> > > > > > Btw, the Learner class has this handy method below (self is a
> >> > > > > QuorumPeer):
> >> > > > > >
> >> > > > > > ---------------- Learner --------------------
> >> > > > > >
> >> > > > > > /**
> >> > > > > > * Returns the address of the node we think is the leader.
> >> > > > > > */
> >> > > > > > protected QuorumServer findLeader() {
> >> > > > > > QuorumServer leaderServer = null;
> >> > > > > > // Find the leader by id
> >> > > > > > Vote current = self.getCurrentVote();
> >> > > > > > for (QuorumServer s : self.getView().values()) {
> >> > > > > > if (s.id == current.getId()) {
> >> > > > > > leaderServer = s;
> >> > > > > > break;
> >> > > > > > }
> >> > > > > > }
> >> > > > > > if (leaderServer == null) {
> >> > > > > > LOG.warn("Couldn't find the leader with id = "
> >> > > > > > + current.getId());
> >> > > > > > }
> >> > > > > > return leaderServer;
> >> > > > > > }
> >> > > > > >
> >> > > > > > ---------------------------------------
> >> > > > > >
> >> > > > > > By the way, as a side note, the map traversal could be changed
> >> by:
> >> > > > > >
> >> > > > > > ----------------------------
> >> > > > > >
> >> > > > > > if (self.getView().contains(current.getId()) {
> >> > > > > >
> >> > > > > > }
> >> > > > > >
> >> > > > > > ---------------------------
> >> > > > > >
> >> > > > > >
> >> > > > > >
> >> > > > > > You can see above this method the quorumPeer.getView()
> returns a
> >> > > > Map<sid,
> >> > > > > > QuorumServer> as below:
> >> > > > > >
> >> > > > > > -------------QuorumPeer ---------
> >> > > > > >
> >> > > > > > /**
> >> > > > > > * A 'view' is a node's current opinion of the membership of
> the
> >> > > entire
> >> > > > > > * ensemble.
> >> > > > > > */
> >> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> >> > > > > > return Collections.unmodifiableMap(getQuorumVerifier().
> >> > > > > > getAllMembers());
> >> > > > > > }
> >> > > > > >
> >> > > > > > -----------------------------
> >> > > > > >
> >> > > > > >
> >> > > > > > And then it retrieves the QuorumServer that has many more
> >> > information
> >> > > > > > about the node besides the sid (InetSocketAddress, hostname,
> >> etc).
> >> > :)
> >> > > > > >
> >> > > > > >
> >> > > > > > Cheers,
> >> > > > > > Edward
> >> > > > > >
> >> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> >> > eolivelli@gmail.com
> >> > > >
> >> > > > > > wrote:
> >> > > > > >
> >> > > > > >> So I am trying to create a patch in order to expose on JMX
> the
> >> id
> >> > of
> >> > > > the
> >> > > > > >> current "leader" (on the JVM of a follower)
> >> > > > > >>
> >> > > > > >> I am trying to find in ZK which is the variable which holds
> >> the ID
> >> > > of
> >> > > > > the
> >> > > > > >> current leader.
> >> > > > > >> I am new to the internal of QuorumPeer
> >> > > > > >>
> >> > > > > >> Can someone give me some hint ?
> >> > > > > >>
> >> > > > > >> Enrico
> >> > > > > >>
> >> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> >> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> >> > > > > >>
> >> > > > > >> > Hi,
> >> > > > > >> > That is possible with 4 letter commands. We are using it
> >> now. In
> >> > > > 3.5.x
> >> > > > > >> it
> >> > > > > >> > is going to be removed in favour of admin server (embedded
> >> web
> >> > > > > server).
> >> > > > > >> > We are running in an environment where it’s not possible to
> >> run
> >> > > JMX
> >> > > > or
> >> > > > > >> > embedded web servers.
> >> > > > > >> >
> >> > > > > >> > So I am wondering if there is another way? It would be nice
> >> to
> >> > > have
> >> > > > > this
> >> > > > > >> > info as a znode.
> >> > > > > >> >
> >> > > > > >> > Best regards,
> >> > > > > >> > Ansel
> >> > > > > >> >
> >> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <
> fpj@apache.org>
> >> > > wrote:
> >> > > > > >> > >
> >> > > > > >> > > Hi Enrico,
> >> > > > > >> > >
> >> > > > > >> > > You can determine the state of a server it via 4-letter
> >> > > commands.
> >> > > > > >> Would
> >> > > > > >> > that work for you?
> >> > > > > >> > >
> >> > > > > >> > > -Flavio
> >> > > > > >> > >
> >> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> >> > eolivelli@gmail.com>
> >> > > > > >> wrote:
> >> > > > > >> > >>
> >> > > > > >> > >> Hi,
> >> > > > > >> > >> is there any way to see in JMX which is the leader of a
> >> > > ZooKeeper
> >> > > > > >> > cluster?
> >> > > > > >> > >>
> >> > > > > >> > >> My problem is: given access to any of the nodes of the
> >> > cluster
> >> > > I
> >> > > > > >> want to
> >> > > > > >> > >> know from JMX which is the current leader.
> >> > > > > >> > >> It seems to me that this information is not available,
> you
> >> > can
> >> > > > know
> >> > > > > >> > only if
> >> > > > > >> > >> the local node is Leader or Follower.
> >> > > > > >> > >>
> >> > > > > >> > >> Cheers
> >> > > > > >> > >> Enrico
> >> > > > > >> > >
> >> > > > > >> >
> >> > > > > >> >
> >> > > > > >>
> >> > > > > >
> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> >> >
> >>
> > --
> >
> >
> > -- Enrico Olivelli
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
This is my patch
https://github.com/apache/zookeeper/pull/546
One question:
I would like to force the cluster to change leader in
HierarchicalQuorumTest, so that I can test that JMX will reflect the new
status of the group.
Any idea about how to bounce the leader ?
Cheers
Enrico
Il giorno mer 20 giu 2018 alle ore 13:45 Enrico Olivelli <
eolivelli@gmail.com> ha scritto:
> This is my JIRA
> I am going to work on a patch
>
> https://issues.apache.org/jira/browse/ZOOKEEPER-3066
>
> Enrico
>
> Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha scritto:
>
>> "in order to guess which is the leader I have to ask to all of the three
>> nodes in the cluster"
>>
>> That's correct.
>>
>> Regards,
>> Andor
>>
>>
>>
>> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eo...@gmail.com>
>> wrote:
>>
>> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <ph...@apache.org>
>> ha
>> > scritto:
>> >
>> > > iiuc what you are interested in the information is already available.
>> The
>> > > beans have a "state" attribute which indicates following vs leading.
>> > >
>> > > Try attaching a jconsole to the running servers, use the "mbeans" tab
>> and
>> > > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
>> > > attributes, you'll see the "state" attribute there.
>> > >
>> >
>> >
>> > Patrick,
>> > I can't find this information.
>> > If I log into a "follower" I get this info only for the 'current
>> replica'
>> >
>> > Example, I have three peers, the first one is a "Follower", on JMX I
>> have
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ClientAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
>> ElectionAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - QuorumAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
>> > following
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ConfigVersion
>> > .....
>> >
>> >
>> >
>> > for other peers I see only
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ClientAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
>> ElectionAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - QuorumAddress
>> >
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ClientAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
>> ElectionAddress
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
>> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - QuorumAddress
>> >
>> >
>> > so quering only this server I cannot guess which is the current leader,
>> the
>> > only information I can extract is:
>> > - I am a follower
>> > - We are a cluster of three
>> > - Every of the three is a PARTECIPANT (no observers)
>> >
>> > in order to guess which is the leader I have to ask to all of the three
>> > nodes in the cluster
>> >
>> > Am I missing something ? I am running 3.5.3-BETA
>> >
>> > Enrico
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > >
>> > > Patrick
>> > >
>> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com>
>> > > wrote:
>> > >
>> > > > Thank you Edward
>> > > >
>> > > > I will pack all together and send out a patch as soon as I have
>> time.
>> > > > I am running 3.5 in production and given than an RC for 3.5.4 is
>> going
>> > to
>> > > > be cut soon I will have to wait for 3.5.5 and I assume it won't be
>> > > > immediate.
>> > > >
>> > > > Cheers
>> > > > Enrico
>> > > >
>> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
>> > > > edward.ribeiro@gmail.com> ha scritto:
>> > > >
>> > > > > Sent before finishing the previous email. Only to complement, the
>> > > > > findLeader() could have been as below, but this change is only a
>> > nitty
>> > > > > detail and totally irrelevant to the questions you are asking. :)
>> > > > >
>> > > > > /**
>> > > > > * Returns the address of the node we think is the leader.
>> > > > > */
>> > > > > protected QuorumServer findLeader() {
>> > > > >
>> > > > > // Find the leader by id
>> > > > > long currentLeader = self.getCurrentVote().getId();
>> > > > >
>> > > > > QuorumServer leaderServer = self.getView().get(currentLeader);
>> > > > >
>> > > > > if (leaderServer == null) {
>> > > > > LOG.warn("Couldn't find the leader with id = {}",
>> > > currentLeader);
>> > > > > }
>> > > > > return leaderServer;
>> > > > > }
>> > > > >
>> > > > > Edward
>> > > > >
>> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
>> > > edward.ribeiro@gmail.com
>> > > > >
>> > > > > wrote:
>> > > > >
>> > > > > > Hi Enrico,
>> > > > > >
>> > > > > > Well, I am not an expert on QuorumPeer either (not an expert on
>> > > > anything,
>> > > > > > really), but maybe it's the variable and method below?
>> > > > > >
>> > > > > > ----------------- QuorumPeer ------------------
>> > > > > >
>> > > > > > /**
>> > > > > > * This is who I think the leader currently is.
>> > > > > > */
>> > > > > > volatile private Vote currentVote;
>> > > > > >
>> > > > > > public synchronized Vote getCurrentVote(){
>> > > > > > return currentVote;
>> > > > > > }
>> > > > > >
>> > > > > > ---------------------------------------
>> > > > > >
>> > > > > >
>> > > > > > Then it's a matter of calling
>> quorumPeer.getCurrentVote().getId()
>> > and
>> > > > > > quorumPeer.getServerState()?
>> > > > > >
>> > > > > > Btw, the Learner class has this handy method below (self is a
>> > > > > QuorumPeer):
>> > > > > >
>> > > > > > ---------------- Learner --------------------
>> > > > > >
>> > > > > > /**
>> > > > > > * Returns the address of the node we think is the leader.
>> > > > > > */
>> > > > > > protected QuorumServer findLeader() {
>> > > > > > QuorumServer leaderServer = null;
>> > > > > > // Find the leader by id
>> > > > > > Vote current = self.getCurrentVote();
>> > > > > > for (QuorumServer s : self.getView().values()) {
>> > > > > > if (s.id == current.getId()) {
>> > > > > > leaderServer = s;
>> > > > > > break;
>> > > > > > }
>> > > > > > }
>> > > > > > if (leaderServer == null) {
>> > > > > > LOG.warn("Couldn't find the leader with id = "
>> > > > > > + current.getId());
>> > > > > > }
>> > > > > > return leaderServer;
>> > > > > > }
>> > > > > >
>> > > > > > ---------------------------------------
>> > > > > >
>> > > > > > By the way, as a side note, the map traversal could be changed
>> by:
>> > > > > >
>> > > > > > ----------------------------
>> > > > > >
>> > > > > > if (self.getView().contains(current.getId()) {
>> > > > > >
>> > > > > > }
>> > > > > >
>> > > > > > ---------------------------
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > You can see above this method the quorumPeer.getView() returns a
>> > > > Map<sid,
>> > > > > > QuorumServer> as below:
>> > > > > >
>> > > > > > -------------QuorumPeer ---------
>> > > > > >
>> > > > > > /**
>> > > > > > * A 'view' is a node's current opinion of the membership of the
>> > > entire
>> > > > > > * ensemble.
>> > > > > > */
>> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
>> > > > > > return Collections.unmodifiableMap(getQuorumVerifier().
>> > > > > > getAllMembers());
>> > > > > > }
>> > > > > >
>> > > > > > -----------------------------
>> > > > > >
>> > > > > >
>> > > > > > And then it retrieves the QuorumServer that has many more
>> > information
>> > > > > > about the node besides the sid (InetSocketAddress, hostname,
>> etc).
>> > :)
>> > > > > >
>> > > > > >
>> > > > > > Cheers,
>> > > > > > Edward
>> > > > > >
>> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
>> > eolivelli@gmail.com
>> > > >
>> > > > > > wrote:
>> > > > > >
>> > > > > >> So I am trying to create a patch in order to expose on JMX the
>> id
>> > of
>> > > > the
>> > > > > >> current "leader" (on the JVM of a follower)
>> > > > > >>
>> > > > > >> I am trying to find in ZK which is the variable which holds
>> the ID
>> > > of
>> > > > > the
>> > > > > >> current leader.
>> > > > > >> I am new to the internal of QuorumPeer
>> > > > > >>
>> > > > > >> Can someone give me some hint ?
>> > > > > >>
>> > > > > >> Enrico
>> > > > > >>
>> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
>> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
>> > > > > >>
>> > > > > >> > Hi,
>> > > > > >> > That is possible with 4 letter commands. We are using it
>> now. In
>> > > > 3.5.x
>> > > > > >> it
>> > > > > >> > is going to be removed in favour of admin server (embedded
>> web
>> > > > > server).
>> > > > > >> > We are running in an environment where it’s not possible to
>> run
>> > > JMX
>> > > > or
>> > > > > >> > embedded web servers.
>> > > > > >> >
>> > > > > >> > So I am wondering if there is another way? It would be nice
>> to
>> > > have
>> > > > > this
>> > > > > >> > info as a znode.
>> > > > > >> >
>> > > > > >> > Best regards,
>> > > > > >> > Ansel
>> > > > > >> >
>> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org>
>> > > wrote:
>> > > > > >> > >
>> > > > > >> > > Hi Enrico,
>> > > > > >> > >
>> > > > > >> > > You can determine the state of a server it via 4-letter
>> > > commands.
>> > > > > >> Would
>> > > > > >> > that work for you?
>> > > > > >> > >
>> > > > > >> > > -Flavio
>> > > > > >> > >
>> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
>> > eolivelli@gmail.com>
>> > > > > >> wrote:
>> > > > > >> > >>
>> > > > > >> > >> Hi,
>> > > > > >> > >> is there any way to see in JMX which is the leader of a
>> > > ZooKeeper
>> > > > > >> > cluster?
>> > > > > >> > >>
>> > > > > >> > >> My problem is: given access to any of the nodes of the
>> > cluster
>> > > I
>> > > > > >> want to
>> > > > > >> > >> know from JMX which is the current leader.
>> > > > > >> > >> It seems to me that this information is not available, you
>> > can
>> > > > know
>> > > > > >> > only if
>> > > > > >> > >> the local node is Leader or Follower.
>> > > > > >> > >>
>> > > > > >> > >> Cheers
>> > > > > >> > >> Enrico
>> > > > > >> > >
>> > > > > >> >
>> > > > > >> >
>> > > > > >>
>> > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>>
> --
>
>
> -- Enrico Olivelli
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
This is my JIRA
I am going to work on a patch
https://issues.apache.org/jira/browse/ZOOKEEPER-3066
Enrico
Il gio 10 mag 2018, 19:47 Andor Molnar <an...@cloudera.com> ha scritto:
> "in order to guess which is the leader I have to ask to all of the three
> nodes in the cluster"
>
> That's correct.
>
> Regards,
> Andor
>
>
>
> On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eo...@gmail.com>
> wrote:
>
> > Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <ph...@apache.org>
> ha
> > scritto:
> >
> > > iiuc what you are interested in the information is already available.
> The
> > > beans have a "state" attribute which indicates following vs leading.
> > >
> > > Try attaching a jconsole to the running servers, use the "mbeans" tab
> and
> > > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> > > attributes, you'll see the "state" attribute there.
> > >
> >
> >
> > Patrick,
> > I can't find this information.
> > If I log into a "follower" I get this info only for the 'current replica'
> >
> > Example, I have three peers, the first one is a "Follower", on JMX I
> have
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ClientAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 -
> ElectionAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - QuorumAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> > following
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ConfigVersion
> > .....
> >
> >
> >
> > for other peers I see only
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ClientAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 -
> ElectionAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - QuorumAddress
> >
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ClientAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 -
> ElectionAddress
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> > o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - QuorumAddress
> >
> >
> > so quering only this server I cannot guess which is the current leader,
> the
> > only information I can extract is:
> > - I am a follower
> > - We are a cluster of three
> > - Every of the three is a PARTECIPANT (no observers)
> >
> > in order to guess which is the leader I have to ask to all of the three
> > nodes in the cluster
> >
> > Am I missing something ? I am running 3.5.3-BETA
> >
> > Enrico
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > >
> > > Patrick
> > >
> > > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com>
> > > wrote:
> > >
> > > > Thank you Edward
> > > >
> > > > I will pack all together and send out a patch as soon as I have time.
> > > > I am running 3.5 in production and given than an RC for 3.5.4 is
> going
> > to
> > > > be cut soon I will have to wait for 3.5.5 and I assume it won't be
> > > > immediate.
> > > >
> > > > Cheers
> > > > Enrico
> > > >
> > > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > > edward.ribeiro@gmail.com> ha scritto:
> > > >
> > > > > Sent before finishing the previous email. Only to complement, the
> > > > > findLeader() could have been as below, but this change is only a
> > nitty
> > > > > detail and totally irrelevant to the questions you are asking. :)
> > > > >
> > > > > /**
> > > > > * Returns the address of the node we think is the leader.
> > > > > */
> > > > > protected QuorumServer findLeader() {
> > > > >
> > > > > // Find the leader by id
> > > > > long currentLeader = self.getCurrentVote().getId();
> > > > >
> > > > > QuorumServer leaderServer = self.getView().get(currentLeader);
> > > > >
> > > > > if (leaderServer == null) {
> > > > > LOG.warn("Couldn't find the leader with id = {}",
> > > currentLeader);
> > > > > }
> > > > > return leaderServer;
> > > > > }
> > > > >
> > > > > Edward
> > > > >
> > > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > > edward.ribeiro@gmail.com
> > > > >
> > > > > wrote:
> > > > >
> > > > > > Hi Enrico,
> > > > > >
> > > > > > Well, I am not an expert on QuorumPeer either (not an expert on
> > > > anything,
> > > > > > really), but maybe it's the variable and method below?
> > > > > >
> > > > > > ----------------- QuorumPeer ------------------
> > > > > >
> > > > > > /**
> > > > > > * This is who I think the leader currently is.
> > > > > > */
> > > > > > volatile private Vote currentVote;
> > > > > >
> > > > > > public synchronized Vote getCurrentVote(){
> > > > > > return currentVote;
> > > > > > }
> > > > > >
> > > > > > ---------------------------------------
> > > > > >
> > > > > >
> > > > > > Then it's a matter of calling quorumPeer.getCurrentVote().getId()
> > and
> > > > > > quorumPeer.getServerState()?
> > > > > >
> > > > > > Btw, the Learner class has this handy method below (self is a
> > > > > QuorumPeer):
> > > > > >
> > > > > > ---------------- Learner --------------------
> > > > > >
> > > > > > /**
> > > > > > * Returns the address of the node we think is the leader.
> > > > > > */
> > > > > > protected QuorumServer findLeader() {
> > > > > > QuorumServer leaderServer = null;
> > > > > > // Find the leader by id
> > > > > > Vote current = self.getCurrentVote();
> > > > > > for (QuorumServer s : self.getView().values()) {
> > > > > > if (s.id == current.getId()) {
> > > > > > leaderServer = s;
> > > > > > break;
> > > > > > }
> > > > > > }
> > > > > > if (leaderServer == null) {
> > > > > > LOG.warn("Couldn't find the leader with id = "
> > > > > > + current.getId());
> > > > > > }
> > > > > > return leaderServer;
> > > > > > }
> > > > > >
> > > > > > ---------------------------------------
> > > > > >
> > > > > > By the way, as a side note, the map traversal could be changed
> by:
> > > > > >
> > > > > > ----------------------------
> > > > > >
> > > > > > if (self.getView().contains(current.getId()) {
> > > > > >
> > > > > > }
> > > > > >
> > > > > > ---------------------------
> > > > > >
> > > > > >
> > > > > >
> > > > > > You can see above this method the quorumPeer.getView() returns a
> > > > Map<sid,
> > > > > > QuorumServer> as below:
> > > > > >
> > > > > > -------------QuorumPeer ---------
> > > > > >
> > > > > > /**
> > > > > > * A 'view' is a node's current opinion of the membership of the
> > > entire
> > > > > > * ensemble.
> > > > > > */
> > > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > > > return Collections.unmodifiableMap(getQuorumVerifier().
> > > > > > getAllMembers());
> > > > > > }
> > > > > >
> > > > > > -----------------------------
> > > > > >
> > > > > >
> > > > > > And then it retrieves the QuorumServer that has many more
> > information
> > > > > > about the node besides the sid (InetSocketAddress, hostname,
> etc).
> > :)
> > > > > >
> > > > > >
> > > > > > Cheers,
> > > > > > Edward
> > > > > >
> > > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> > eolivelli@gmail.com
> > > >
> > > > > > wrote:
> > > > > >
> > > > > >> So I am trying to create a patch in order to expose on JMX the
> id
> > of
> > > > the
> > > > > >> current "leader" (on the JVM of a follower)
> > > > > >>
> > > > > >> I am trying to find in ZK which is the variable which holds the
> ID
> > > of
> > > > > the
> > > > > >> current leader.
> > > > > >> I am new to the internal of QuorumPeer
> > > > > >>
> > > > > >> Can someone give me some hint ?
> > > > > >>
> > > > > >> Enrico
> > > > > >>
> > > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > > >>
> > > > > >> > Hi,
> > > > > >> > That is possible with 4 letter commands. We are using it now.
> In
> > > > 3.5.x
> > > > > >> it
> > > > > >> > is going to be removed in favour of admin server (embedded web
> > > > > server).
> > > > > >> > We are running in an environment where it’s not possible to
> run
> > > JMX
> > > > or
> > > > > >> > embedded web servers.
> > > > > >> >
> > > > > >> > So I am wondering if there is another way? It would be nice to
> > > have
> > > > > this
> > > > > >> > info as a znode.
> > > > > >> >
> > > > > >> > Best regards,
> > > > > >> > Ansel
> > > > > >> >
> > > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org>
> > > wrote:
> > > > > >> > >
> > > > > >> > > Hi Enrico,
> > > > > >> > >
> > > > > >> > > You can determine the state of a server it via 4-letter
> > > commands.
> > > > > >> Would
> > > > > >> > that work for you?
> > > > > >> > >
> > > > > >> > > -Flavio
> > > > > >> > >
> > > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> > eolivelli@gmail.com>
> > > > > >> wrote:
> > > > > >> > >>
> > > > > >> > >> Hi,
> > > > > >> > >> is there any way to see in JMX which is the leader of a
> > > ZooKeeper
> > > > > >> > cluster?
> > > > > >> > >>
> > > > > >> > >> My problem is: given access to any of the nodes of the
> > cluster
> > > I
> > > > > >> want to
> > > > > >> > >> know from JMX which is the current leader.
> > > > > >> > >> It seems to me that this information is not available, you
> > can
> > > > know
> > > > > >> > only if
> > > > > >> > >> the local node is Leader or Follower.
> > > > > >> > >>
> > > > > >> > >> Cheers
> > > > > >> > >> Enrico
> > > > > >> > >
> > > > > >> >
> > > > > >> >
> > > > > >>
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
--
-- Enrico Olivelli
Re: Discover LEADER from JMX
Posted by Andor Molnar <an...@cloudera.com>.
"in order to guess which is the leader I have to ask to all of the three
nodes in the cluster"
That's correct.
Regards,
Andor
On Thu, May 10, 2018 at 4:07 AM, Enrico Olivelli <eo...@gmail.com>
wrote:
> Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <ph...@apache.org> ha
> scritto:
>
> > iiuc what you are interested in the information is already available. The
> > beans have a "state" attribute which indicates following vs leading.
> >
> > Try attaching a jconsole to the running servers, use the "mbeans" tab and
> > open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> > attributes, you'll see the "state" attribute there.
> >
>
>
> Patrick,
> I can't find this information.
> If I log into a "follower" I get this info only for the 'current replica'
>
> Example, I have three peers, the first one is a "Follower", on JMX I have
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - QuorumAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State =
> following
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ConfigVersion
> .....
>
>
>
> for other peers I see only
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - QuorumAddress
>
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ClientAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ElectionAddress
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
> o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - QuorumAddress
>
>
> so quering only this server I cannot guess which is the current leader, the
> only information I can extract is:
> - I am a follower
> - We are a cluster of three
> - Every of the three is a PARTECIPANT (no observers)
>
> in order to guess which is the leader I have to ask to all of the three
> nodes in the cluster
>
> Am I missing something ? I am running 3.5.3-BETA
>
> Enrico
>
>
>
>
>
>
>
>
>
>
>
>
>
> >
> > Patrick
> >
> > On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com>
> > wrote:
> >
> > > Thank you Edward
> > >
> > > I will pack all together and send out a patch as soon as I have time.
> > > I am running 3.5 in production and given than an RC for 3.5.4 is going
> to
> > > be cut soon I will have to wait for 3.5.5 and I assume it won't be
> > > immediate.
> > >
> > > Cheers
> > > Enrico
> > >
> > > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > > edward.ribeiro@gmail.com> ha scritto:
> > >
> > > > Sent before finishing the previous email. Only to complement, the
> > > > findLeader() could have been as below, but this change is only a
> nitty
> > > > detail and totally irrelevant to the questions you are asking. :)
> > > >
> > > > /**
> > > > * Returns the address of the node we think is the leader.
> > > > */
> > > > protected QuorumServer findLeader() {
> > > >
> > > > // Find the leader by id
> > > > long currentLeader = self.getCurrentVote().getId();
> > > >
> > > > QuorumServer leaderServer = self.getView().get(currentLeader);
> > > >
> > > > if (leaderServer == null) {
> > > > LOG.warn("Couldn't find the leader with id = {}",
> > currentLeader);
> > > > }
> > > > return leaderServer;
> > > > }
> > > >
> > > > Edward
> > > >
> > > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> > edward.ribeiro@gmail.com
> > > >
> > > > wrote:
> > > >
> > > > > Hi Enrico,
> > > > >
> > > > > Well, I am not an expert on QuorumPeer either (not an expert on
> > > anything,
> > > > > really), but maybe it's the variable and method below?
> > > > >
> > > > > ----------------- QuorumPeer ------------------
> > > > >
> > > > > /**
> > > > > * This is who I think the leader currently is.
> > > > > */
> > > > > volatile private Vote currentVote;
> > > > >
> > > > > public synchronized Vote getCurrentVote(){
> > > > > return currentVote;
> > > > > }
> > > > >
> > > > > ---------------------------------------
> > > > >
> > > > >
> > > > > Then it's a matter of calling quorumPeer.getCurrentVote().getId()
> and
> > > > > quorumPeer.getServerState()?
> > > > >
> > > > > Btw, the Learner class has this handy method below (self is a
> > > > QuorumPeer):
> > > > >
> > > > > ---------------- Learner --------------------
> > > > >
> > > > > /**
> > > > > * Returns the address of the node we think is the leader.
> > > > > */
> > > > > protected QuorumServer findLeader() {
> > > > > QuorumServer leaderServer = null;
> > > > > // Find the leader by id
> > > > > Vote current = self.getCurrentVote();
> > > > > for (QuorumServer s : self.getView().values()) {
> > > > > if (s.id == current.getId()) {
> > > > > leaderServer = s;
> > > > > break;
> > > > > }
> > > > > }
> > > > > if (leaderServer == null) {
> > > > > LOG.warn("Couldn't find the leader with id = "
> > > > > + current.getId());
> > > > > }
> > > > > return leaderServer;
> > > > > }
> > > > >
> > > > > ---------------------------------------
> > > > >
> > > > > By the way, as a side note, the map traversal could be changed by:
> > > > >
> > > > > ----------------------------
> > > > >
> > > > > if (self.getView().contains(current.getId()) {
> > > > >
> > > > > }
> > > > >
> > > > > ---------------------------
> > > > >
> > > > >
> > > > >
> > > > > You can see above this method the quorumPeer.getView() returns a
> > > Map<sid,
> > > > > QuorumServer> as below:
> > > > >
> > > > > -------------QuorumPeer ---------
> > > > >
> > > > > /**
> > > > > * A 'view' is a node's current opinion of the membership of the
> > entire
> > > > > * ensemble.
> > > > > */
> > > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > > return Collections.unmodifiableMap(getQuorumVerifier().
> > > > > getAllMembers());
> > > > > }
> > > > >
> > > > > -----------------------------
> > > > >
> > > > >
> > > > > And then it retrieves the QuorumServer that has many more
> information
> > > > > about the node besides the sid (InetSocketAddress, hostname, etc).
> :)
> > > > >
> > > > >
> > > > > Cheers,
> > > > > Edward
> > > > >
> > > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <
> eolivelli@gmail.com
> > >
> > > > > wrote:
> > > > >
> > > > >> So I am trying to create a patch in order to expose on JMX the id
> of
> > > the
> > > > >> current "leader" (on the JVM of a follower)
> > > > >>
> > > > >> I am trying to find in ZK which is the variable which holds the ID
> > of
> > > > the
> > > > >> current leader.
> > > > >> I am new to the internal of QuorumPeer
> > > > >>
> > > > >> Can someone give me some hint ?
> > > > >>
> > > > >> Enrico
> > > > >>
> > > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > > >>
> > > > >> > Hi,
> > > > >> > That is possible with 4 letter commands. We are using it now. In
> > > 3.5.x
> > > > >> it
> > > > >> > is going to be removed in favour of admin server (embedded web
> > > > server).
> > > > >> > We are running in an environment where it’s not possible to run
> > JMX
> > > or
> > > > >> > embedded web servers.
> > > > >> >
> > > > >> > So I am wondering if there is another way? It would be nice to
> > have
> > > > this
> > > > >> > info as a znode.
> > > > >> >
> > > > >> > Best regards,
> > > > >> > Ansel
> > > > >> >
> > > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org>
> > wrote:
> > > > >> > >
> > > > >> > > Hi Enrico,
> > > > >> > >
> > > > >> > > You can determine the state of a server it via 4-letter
> > commands.
> > > > >> Would
> > > > >> > that work for you?
> > > > >> > >
> > > > >> > > -Flavio
> > > > >> > >
> > > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <
> eolivelli@gmail.com>
> > > > >> wrote:
> > > > >> > >>
> > > > >> > >> Hi,
> > > > >> > >> is there any way to see in JMX which is the leader of a
> > ZooKeeper
> > > > >> > cluster?
> > > > >> > >>
> > > > >> > >> My problem is: given access to any of the nodes of the
> cluster
> > I
> > > > >> want to
> > > > >> > >> know from JMX which is the current leader.
> > > > >> > >> It seems to me that this information is not available, you
> can
> > > know
> > > > >> > only if
> > > > >> > >> the local node is Leader or Follower.
> > > > >> > >>
> > > > >> > >> Cheers
> > > > >> > >> Enrico
> > > > >> > >
> > > > >> >
> > > > >> >
> > > > >>
> > > > >
> > > > >
> > > >
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Il giorno mer 9 mag 2018 alle ore 20:24 Patrick Hunt <ph...@apache.org> ha
scritto:
> iiuc what you are interested in the information is already available. The
> beans have a "state" attribute which indicates following vs leading.
>
> Try attaching a jconsole to the running servers, use the "mbeans" tab and
> open org.apache.ZooKeeperService -> replicatedserver -> replica ->
> attributes, you'll see the "state" attribute there.
>
Patrick,
I can't find this information.
If I log into a "follower" I get this info only for the 'current replica'
Example, I have three peers, the first one is a "Follower", on JMX I have
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ClientAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ElectionAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - LearnerType
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - Name
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - QuorumAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - State = following
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_1 - ConfigVersion
.....
for other peers I see only
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ClientAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - ElectionAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - LearnerType
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - Name
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_2 - QuorumAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ClientAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - ElectionAddress
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - LearnerType
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - Name
o.a.ZookKeeperService - ReplicatedServer_id1 - replica_3 - QuorumAddress
so quering only this server I cannot guess which is the current leader, the
only information I can extract is:
- I am a follower
- We are a cluster of three
- Every of the three is a PARTECIPANT (no observers)
in order to guess which is the leader I have to ask to all of the three
nodes in the cluster
Am I missing something ? I am running 3.5.3-BETA
Enrico
>
> Patrick
>
> On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com>
> wrote:
>
> > Thank you Edward
> >
> > I will pack all together and send out a patch as soon as I have time.
> > I am running 3.5 in production and given than an RC for 3.5.4 is going to
> > be cut soon I will have to wait for 3.5.5 and I assume it won't be
> > immediate.
> >
> > Cheers
> > Enrico
> >
> > Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> > edward.ribeiro@gmail.com> ha scritto:
> >
> > > Sent before finishing the previous email. Only to complement, the
> > > findLeader() could have been as below, but this change is only a nitty
> > > detail and totally irrelevant to the questions you are asking. :)
> > >
> > > /**
> > > * Returns the address of the node we think is the leader.
> > > */
> > > protected QuorumServer findLeader() {
> > >
> > > // Find the leader by id
> > > long currentLeader = self.getCurrentVote().getId();
> > >
> > > QuorumServer leaderServer = self.getView().get(currentLeader);
> > >
> > > if (leaderServer == null) {
> > > LOG.warn("Couldn't find the leader with id = {}",
> currentLeader);
> > > }
> > > return leaderServer;
> > > }
> > >
> > > Edward
> > >
> > > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <
> edward.ribeiro@gmail.com
> > >
> > > wrote:
> > >
> > > > Hi Enrico,
> > > >
> > > > Well, I am not an expert on QuorumPeer either (not an expert on
> > anything,
> > > > really), but maybe it's the variable and method below?
> > > >
> > > > ----------------- QuorumPeer ------------------
> > > >
> > > > /**
> > > > * This is who I think the leader currently is.
> > > > */
> > > > volatile private Vote currentVote;
> > > >
> > > > public synchronized Vote getCurrentVote(){
> > > > return currentVote;
> > > > }
> > > >
> > > > ---------------------------------------
> > > >
> > > >
> > > > Then it's a matter of calling quorumPeer.getCurrentVote().getId() and
> > > > quorumPeer.getServerState()?
> > > >
> > > > Btw, the Learner class has this handy method below (self is a
> > > QuorumPeer):
> > > >
> > > > ---------------- Learner --------------------
> > > >
> > > > /**
> > > > * Returns the address of the node we think is the leader.
> > > > */
> > > > protected QuorumServer findLeader() {
> > > > QuorumServer leaderServer = null;
> > > > // Find the leader by id
> > > > Vote current = self.getCurrentVote();
> > > > for (QuorumServer s : self.getView().values()) {
> > > > if (s.id == current.getId()) {
> > > > leaderServer = s;
> > > > break;
> > > > }
> > > > }
> > > > if (leaderServer == null) {
> > > > LOG.warn("Couldn't find the leader with id = "
> > > > + current.getId());
> > > > }
> > > > return leaderServer;
> > > > }
> > > >
> > > > ---------------------------------------
> > > >
> > > > By the way, as a side note, the map traversal could be changed by:
> > > >
> > > > ----------------------------
> > > >
> > > > if (self.getView().contains(current.getId()) {
> > > >
> > > > }
> > > >
> > > > ---------------------------
> > > >
> > > >
> > > >
> > > > You can see above this method the quorumPeer.getView() returns a
> > Map<sid,
> > > > QuorumServer> as below:
> > > >
> > > > -------------QuorumPeer ---------
> > > >
> > > > /**
> > > > * A 'view' is a node's current opinion of the membership of the
> entire
> > > > * ensemble.
> > > > */
> > > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > > return Collections.unmodifiableMap(getQuorumVerifier().
> > > > getAllMembers());
> > > > }
> > > >
> > > > -----------------------------
> > > >
> > > >
> > > > And then it retrieves the QuorumServer that has many more information
> > > > about the node besides the sid (InetSocketAddress, hostname, etc). :)
> > > >
> > > >
> > > > Cheers,
> > > > Edward
> > > >
> > > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <eolivelli@gmail.com
> >
> > > > wrote:
> > > >
> > > >> So I am trying to create a patch in order to expose on JMX the id of
> > the
> > > >> current "leader" (on the JVM of a follower)
> > > >>
> > > >> I am trying to find in ZK which is the variable which holds the ID
> of
> > > the
> > > >> current leader.
> > > >> I am new to the internal of QuorumPeer
> > > >>
> > > >> Can someone give me some hint ?
> > > >>
> > > >> Enrico
> > > >>
> > > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > > >> Ansel.Zandegran@infor.com> ha scritto:
> > > >>
> > > >> > Hi,
> > > >> > That is possible with 4 letter commands. We are using it now. In
> > 3.5.x
> > > >> it
> > > >> > is going to be removed in favour of admin server (embedded web
> > > server).
> > > >> > We are running in an environment where it’s not possible to run
> JMX
> > or
> > > >> > embedded web servers.
> > > >> >
> > > >> > So I am wondering if there is another way? It would be nice to
> have
> > > this
> > > >> > info as a znode.
> > > >> >
> > > >> > Best regards,
> > > >> > Ansel
> > > >> >
> > > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org>
> wrote:
> > > >> > >
> > > >> > > Hi Enrico,
> > > >> > >
> > > >> > > You can determine the state of a server it via 4-letter
> commands.
> > > >> Would
> > > >> > that work for you?
> > > >> > >
> > > >> > > -Flavio
> > > >> > >
> > > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com>
> > > >> wrote:
> > > >> > >>
> > > >> > >> Hi,
> > > >> > >> is there any way to see in JMX which is the leader of a
> ZooKeeper
> > > >> > cluster?
> > > >> > >>
> > > >> > >> My problem is: given access to any of the nodes of the cluster
> I
> > > >> want to
> > > >> > >> know from JMX which is the current leader.
> > > >> > >> It seems to me that this information is not available, you can
> > know
> > > >> > only if
> > > >> > >> the local node is Leader or Follower.
> > > >> > >>
> > > >> > >> Cheers
> > > >> > >> Enrico
> > > >> > >
> > > >> >
> > > >> >
> > > >>
> > > >
> > > >
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Patrick Hunt <ph...@apache.org>.
iiuc what you are interested in the information is already available. The
beans have a "state" attribute which indicates following vs leading.
Try attaching a jconsole to the running servers, use the "mbeans" tab and
open org.apache.ZooKeeperService -> replicatedserver -> replica ->
attributes, you'll see the "state" attribute there.
Patrick
On Wed, May 9, 2018 at 8:02 AM, Enrico Olivelli <eo...@gmail.com> wrote:
> Thank you Edward
>
> I will pack all together and send out a patch as soon as I have time.
> I am running 3.5 in production and given than an RC for 3.5.4 is going to
> be cut soon I will have to wait for 3.5.5 and I assume it won't be
> immediate.
>
> Cheers
> Enrico
>
> Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
> edward.ribeiro@gmail.com> ha scritto:
>
> > Sent before finishing the previous email. Only to complement, the
> > findLeader() could have been as below, but this change is only a nitty
> > detail and totally irrelevant to the questions you are asking. :)
> >
> > /**
> > * Returns the address of the node we think is the leader.
> > */
> > protected QuorumServer findLeader() {
> >
> > // Find the leader by id
> > long currentLeader = self.getCurrentVote().getId();
> >
> > QuorumServer leaderServer = self.getView().get(currentLeader);
> >
> > if (leaderServer == null) {
> > LOG.warn("Couldn't find the leader with id = {}", currentLeader);
> > }
> > return leaderServer;
> > }
> >
> > Edward
> >
> > On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <edward.ribeiro@gmail.com
> >
> > wrote:
> >
> > > Hi Enrico,
> > >
> > > Well, I am not an expert on QuorumPeer either (not an expert on
> anything,
> > > really), but maybe it's the variable and method below?
> > >
> > > ----------------- QuorumPeer ------------------
> > >
> > > /**
> > > * This is who I think the leader currently is.
> > > */
> > > volatile private Vote currentVote;
> > >
> > > public synchronized Vote getCurrentVote(){
> > > return currentVote;
> > > }
> > >
> > > ---------------------------------------
> > >
> > >
> > > Then it's a matter of calling quorumPeer.getCurrentVote().getId() and
> > > quorumPeer.getServerState()?
> > >
> > > Btw, the Learner class has this handy method below (self is a
> > QuorumPeer):
> > >
> > > ---------------- Learner --------------------
> > >
> > > /**
> > > * Returns the address of the node we think is the leader.
> > > */
> > > protected QuorumServer findLeader() {
> > > QuorumServer leaderServer = null;
> > > // Find the leader by id
> > > Vote current = self.getCurrentVote();
> > > for (QuorumServer s : self.getView().values()) {
> > > if (s.id == current.getId()) {
> > > leaderServer = s;
> > > break;
> > > }
> > > }
> > > if (leaderServer == null) {
> > > LOG.warn("Couldn't find the leader with id = "
> > > + current.getId());
> > > }
> > > return leaderServer;
> > > }
> > >
> > > ---------------------------------------
> > >
> > > By the way, as a side note, the map traversal could be changed by:
> > >
> > > ----------------------------
> > >
> > > if (self.getView().contains(current.getId()) {
> > >
> > > }
> > >
> > > ---------------------------
> > >
> > >
> > >
> > > You can see above this method the quorumPeer.getView() returns a
> Map<sid,
> > > QuorumServer> as below:
> > >
> > > -------------QuorumPeer ---------
> > >
> > > /**
> > > * A 'view' is a node's current opinion of the membership of the entire
> > > * ensemble.
> > > */
> > > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > > return Collections.unmodifiableMap(getQuorumVerifier().
> > > getAllMembers());
> > > }
> > >
> > > -----------------------------
> > >
> > >
> > > And then it retrieves the QuorumServer that has many more information
> > > about the node besides the sid (InetSocketAddress, hostname, etc). :)
> > >
> > >
> > > Cheers,
> > > Edward
> > >
> > > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <eo...@gmail.com>
> > > wrote:
> > >
> > >> So I am trying to create a patch in order to expose on JMX the id of
> the
> > >> current "leader" (on the JVM of a follower)
> > >>
> > >> I am trying to find in ZK which is the variable which holds the ID of
> > the
> > >> current leader.
> > >> I am new to the internal of QuorumPeer
> > >>
> > >> Can someone give me some hint ?
> > >>
> > >> Enrico
> > >>
> > >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> > >> Ansel.Zandegran@infor.com> ha scritto:
> > >>
> > >> > Hi,
> > >> > That is possible with 4 letter commands. We are using it now. In
> 3.5.x
> > >> it
> > >> > is going to be removed in favour of admin server (embedded web
> > server).
> > >> > We are running in an environment where it’s not possible to run JMX
> or
> > >> > embedded web servers.
> > >> >
> > >> > So I am wondering if there is another way? It would be nice to have
> > this
> > >> > info as a znode.
> > >> >
> > >> > Best regards,
> > >> > Ansel
> > >> >
> > >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
> > >> > >
> > >> > > Hi Enrico,
> > >> > >
> > >> > > You can determine the state of a server it via 4-letter commands.
> > >> Would
> > >> > that work for you?
> > >> > >
> > >> > > -Flavio
> > >> > >
> > >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com>
> > >> wrote:
> > >> > >>
> > >> > >> Hi,
> > >> > >> is there any way to see in JMX which is the leader of a ZooKeeper
> > >> > cluster?
> > >> > >>
> > >> > >> My problem is: given access to any of the nodes of the cluster I
> > >> want to
> > >> > >> know from JMX which is the current leader.
> > >> > >> It seems to me that this information is not available, you can
> know
> > >> > only if
> > >> > >> the local node is Leader or Follower.
> > >> > >>
> > >> > >> Cheers
> > >> > >> Enrico
> > >> > >
> > >> >
> > >> >
> > >>
> > >
> > >
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
Thank you Edward
I will pack all together and send out a patch as soon as I have time.
I am running 3.5 in production and given than an RC for 3.5.4 is going to
be cut soon I will have to wait for 3.5.5 and I assume it won't be
immediate.
Cheers
Enrico
Il giorno mer 9 mag 2018 alle ore 14:37 Edward Ribeiro <
edward.ribeiro@gmail.com> ha scritto:
> Sent before finishing the previous email. Only to complement, the
> findLeader() could have been as below, but this change is only a nitty
> detail and totally irrelevant to the questions you are asking. :)
>
> /**
> * Returns the address of the node we think is the leader.
> */
> protected QuorumServer findLeader() {
>
> // Find the leader by id
> long currentLeader = self.getCurrentVote().getId();
>
> QuorumServer leaderServer = self.getView().get(currentLeader);
>
> if (leaderServer == null) {
> LOG.warn("Couldn't find the leader with id = {}", currentLeader);
> }
> return leaderServer;
> }
>
> Edward
>
> On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <ed...@gmail.com>
> wrote:
>
> > Hi Enrico,
> >
> > Well, I am not an expert on QuorumPeer either (not an expert on anything,
> > really), but maybe it's the variable and method below?
> >
> > ----------------- QuorumPeer ------------------
> >
> > /**
> > * This is who I think the leader currently is.
> > */
> > volatile private Vote currentVote;
> >
> > public synchronized Vote getCurrentVote(){
> > return currentVote;
> > }
> >
> > ---------------------------------------
> >
> >
> > Then it's a matter of calling quorumPeer.getCurrentVote().getId() and
> > quorumPeer.getServerState()?
> >
> > Btw, the Learner class has this handy method below (self is a
> QuorumPeer):
> >
> > ---------------- Learner --------------------
> >
> > /**
> > * Returns the address of the node we think is the leader.
> > */
> > protected QuorumServer findLeader() {
> > QuorumServer leaderServer = null;
> > // Find the leader by id
> > Vote current = self.getCurrentVote();
> > for (QuorumServer s : self.getView().values()) {
> > if (s.id == current.getId()) {
> > leaderServer = s;
> > break;
> > }
> > }
> > if (leaderServer == null) {
> > LOG.warn("Couldn't find the leader with id = "
> > + current.getId());
> > }
> > return leaderServer;
> > }
> >
> > ---------------------------------------
> >
> > By the way, as a side note, the map traversal could be changed by:
> >
> > ----------------------------
> >
> > if (self.getView().contains(current.getId()) {
> >
> > }
> >
> > ---------------------------
> >
> >
> >
> > You can see above this method the quorumPeer.getView() returns a Map<sid,
> > QuorumServer> as below:
> >
> > -------------QuorumPeer ---------
> >
> > /**
> > * A 'view' is a node's current opinion of the membership of the entire
> > * ensemble.
> > */
> > public Map<Long,QuorumPeer.QuorumServer> getView() {
> > return Collections.unmodifiableMap(getQuorumVerifier().
> > getAllMembers());
> > }
> >
> > -----------------------------
> >
> >
> > And then it retrieves the QuorumServer that has many more information
> > about the node besides the sid (InetSocketAddress, hostname, etc). :)
> >
> >
> > Cheers,
> > Edward
> >
> > On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <eo...@gmail.com>
> > wrote:
> >
> >> So I am trying to create a patch in order to expose on JMX the id of the
> >> current "leader" (on the JVM of a follower)
> >>
> >> I am trying to find in ZK which is the variable which holds the ID of
> the
> >> current leader.
> >> I am new to the internal of QuorumPeer
> >>
> >> Can someone give me some hint ?
> >>
> >> Enrico
> >>
> >> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> >> Ansel.Zandegran@infor.com> ha scritto:
> >>
> >> > Hi,
> >> > That is possible with 4 letter commands. We are using it now. In 3.5.x
> >> it
> >> > is going to be removed in favour of admin server (embedded web
> server).
> >> > We are running in an environment where it’s not possible to run JMX or
> >> > embedded web servers.
> >> >
> >> > So I am wondering if there is another way? It would be nice to have
> this
> >> > info as a znode.
> >> >
> >> > Best regards,
> >> > Ansel
> >> >
> >> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
> >> > >
> >> > > Hi Enrico,
> >> > >
> >> > > You can determine the state of a server it via 4-letter commands.
> >> Would
> >> > that work for you?
> >> > >
> >> > > -Flavio
> >> > >
> >> > >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com>
> >> wrote:
> >> > >>
> >> > >> Hi,
> >> > >> is there any way to see in JMX which is the leader of a ZooKeeper
> >> > cluster?
> >> > >>
> >> > >> My problem is: given access to any of the nodes of the cluster I
> >> want to
> >> > >> know from JMX which is the current leader.
> >> > >> It seems to me that this information is not available, you can know
> >> > only if
> >> > >> the local node is Leader or Follower.
> >> > >>
> >> > >> Cheers
> >> > >> Enrico
> >> > >
> >> >
> >> >
> >>
> >
> >
>
Re: Discover LEADER from JMX
Posted by Edward Ribeiro <ed...@gmail.com>.
Sent before finishing the previous email. Only to complement, the
findLeader() could have been as below, but this change is only a nitty
detail and totally irrelevant to the questions you are asking. :)
/**
* Returns the address of the node we think is the leader.
*/
protected QuorumServer findLeader() {
// Find the leader by id
long currentLeader = self.getCurrentVote().getId();
QuorumServer leaderServer = self.getView().get(currentLeader);
if (leaderServer == null) {
LOG.warn("Couldn't find the leader with id = {}", currentLeader);
}
return leaderServer;
}
Edward
On Wed, May 9, 2018 at 9:29 AM, Edward Ribeiro <ed...@gmail.com>
wrote:
> Hi Enrico,
>
> Well, I am not an expert on QuorumPeer either (not an expert on anything,
> really), but maybe it's the variable and method below?
>
> ----------------- QuorumPeer ------------------
>
> /**
> * This is who I think the leader currently is.
> */
> volatile private Vote currentVote;
>
> public synchronized Vote getCurrentVote(){
> return currentVote;
> }
>
> ---------------------------------------
>
>
> Then it's a matter of calling quorumPeer.getCurrentVote().getId() and
> quorumPeer.getServerState()?
>
> Btw, the Learner class has this handy method below (self is a QuorumPeer):
>
> ---------------- Learner --------------------
>
> /**
> * Returns the address of the node we think is the leader.
> */
> protected QuorumServer findLeader() {
> QuorumServer leaderServer = null;
> // Find the leader by id
> Vote current = self.getCurrentVote();
> for (QuorumServer s : self.getView().values()) {
> if (s.id == current.getId()) {
> leaderServer = s;
> break;
> }
> }
> if (leaderServer == null) {
> LOG.warn("Couldn't find the leader with id = "
> + current.getId());
> }
> return leaderServer;
> }
>
> ---------------------------------------
>
> By the way, as a side note, the map traversal could be changed by:
>
> ----------------------------
>
> if (self.getView().contains(current.getId()) {
>
> }
>
> ---------------------------
>
>
>
> You can see above this method the quorumPeer.getView() returns a Map<sid,
> QuorumServer> as below:
>
> -------------QuorumPeer ---------
>
> /**
> * A 'view' is a node's current opinion of the membership of the entire
> * ensemble.
> */
> public Map<Long,QuorumPeer.QuorumServer> getView() {
> return Collections.unmodifiableMap(getQuorumVerifier().
> getAllMembers());
> }
>
> -----------------------------
>
>
> And then it retrieves the QuorumServer that has many more information
> about the node besides the sid (InetSocketAddress, hostname, etc). :)
>
>
> Cheers,
> Edward
>
> On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <eo...@gmail.com>
> wrote:
>
>> So I am trying to create a patch in order to expose on JMX the id of the
>> current "leader" (on the JVM of a follower)
>>
>> I am trying to find in ZK which is the variable which holds the ID of the
>> current leader.
>> I am new to the internal of QuorumPeer
>>
>> Can someone give me some hint ?
>>
>> Enrico
>>
>> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
>> Ansel.Zandegran@infor.com> ha scritto:
>>
>> > Hi,
>> > That is possible with 4 letter commands. We are using it now. In 3.5.x
>> it
>> > is going to be removed in favour of admin server (embedded web server).
>> > We are running in an environment where it’s not possible to run JMX or
>> > embedded web servers.
>> >
>> > So I am wondering if there is another way? It would be nice to have this
>> > info as a znode.
>> >
>> > Best regards,
>> > Ansel
>> >
>> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
>> > >
>> > > Hi Enrico,
>> > >
>> > > You can determine the state of a server it via 4-letter commands.
>> Would
>> > that work for you?
>> > >
>> > > -Flavio
>> > >
>> > >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com>
>> wrote:
>> > >>
>> > >> Hi,
>> > >> is there any way to see in JMX which is the leader of a ZooKeeper
>> > cluster?
>> > >>
>> > >> My problem is: given access to any of the nodes of the cluster I
>> want to
>> > >> know from JMX which is the current leader.
>> > >> It seems to me that this information is not available, you can know
>> > only if
>> > >> the local node is Leader or Follower.
>> > >>
>> > >> Cheers
>> > >> Enrico
>> > >
>> >
>> >
>>
>
>
Re: Discover LEADER from JMX
Posted by Edward Ribeiro <ed...@gmail.com>.
Hi Enrico,
Well, I am not an expert on QuorumPeer either (not an expert on anything,
really), but maybe it's the variable and method below?
----------------- QuorumPeer ------------------
/**
* This is who I think the leader currently is.
*/
volatile private Vote currentVote;
public synchronized Vote getCurrentVote(){
return currentVote;
}
---------------------------------------
Then it's a matter of calling quorumPeer.getCurrentVote().getId() and
quorumPeer.getServerState()?
Btw, the Learner class has this handy method below (self is a QuorumPeer):
---------------- Learner --------------------
/**
* Returns the address of the node we think is the leader.
*/
protected QuorumServer findLeader() {
QuorumServer leaderServer = null;
// Find the leader by id
Vote current = self.getCurrentVote();
for (QuorumServer s : self.getView().values()) {
if (s.id == current.getId()) {
leaderServer = s;
break;
}
}
if (leaderServer == null) {
LOG.warn("Couldn't find the leader with id = "
+ current.getId());
}
return leaderServer;
}
---------------------------------------
By the way, as a side note, the map traversal could be changed by:
----------------------------
if (self.getView().contains(current.getId()) {
}
---------------------------
You can see above this method the quorumPeer.getView() returns a Map<sid,
QuorumServer> as below:
-------------QuorumPeer ---------
/**
* A 'view' is a node's current opinion of the membership of the entire
* ensemble.
*/
public Map<Long,QuorumPeer.QuorumServer> getView() {
return Collections.unmodifiableMap(getQuorumVerifier().getAllMembers());
}
-----------------------------
And then it retrieves the QuorumServer that has many more information about
the node besides the sid (InetSocketAddress, hostname, etc). :)
Cheers,
Edward
On Wed, May 9, 2018 at 8:50 AM, Enrico Olivelli <eo...@gmail.com> wrote:
> So I am trying to create a patch in order to expose on JMX the id of the
> current "leader" (on the JVM of a follower)
>
> I am trying to find in ZK which is the variable which holds the ID of the
> current leader.
> I am new to the internal of QuorumPeer
>
> Can someone give me some hint ?
>
> Enrico
>
> Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
> Ansel.Zandegran@infor.com> ha scritto:
>
> > Hi,
> > That is possible with 4 letter commands. We are using it now. In 3.5.x it
> > is going to be removed in favour of admin server (embedded web server).
> > We are running in an environment where it’s not possible to run JMX or
> > embedded web servers.
> >
> > So I am wondering if there is another way? It would be nice to have this
> > info as a znode.
> >
> > Best regards,
> > Ansel
> >
> > > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
> > >
> > > Hi Enrico,
> > >
> > > You can determine the state of a server it via 4-letter commands. Would
> > that work for you?
> > >
> > > -Flavio
> > >
> > >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com> wrote:
> > >>
> > >> Hi,
> > >> is there any way to see in JMX which is the leader of a ZooKeeper
> > cluster?
> > >>
> > >> My problem is: given access to any of the nodes of the cluster I want
> to
> > >> know from JMX which is the current leader.
> > >> It seems to me that this information is not available, you can know
> > only if
> > >> the local node is Leader or Follower.
> > >>
> > >> Cheers
> > >> Enrico
> > >
> >
> >
>
Re: Discover LEADER from JMX
Posted by Enrico Olivelli <eo...@gmail.com>.
So I am trying to create a patch in order to expose on JMX the id of the
current "leader" (on the JVM of a follower)
I am trying to find in ZK which is the variable which holds the ID of the
current leader.
I am new to the internal of QuorumPeer
Can someone give me some hint ?
Enrico
Il giorno mar 8 mag 2018 alle ore 10:08 Ansel Zandegran <
Ansel.Zandegran@infor.com> ha scritto:
> Hi,
> That is possible with 4 letter commands. We are using it now. In 3.5.x it
> is going to be removed in favour of admin server (embedded web server).
> We are running in an environment where it’s not possible to run JMX or
> embedded web servers.
>
> So I am wondering if there is another way? It would be nice to have this
> info as a znode.
>
> Best regards,
> Ansel
>
> > On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
> >
> > Hi Enrico,
> >
> > You can determine the state of a server it via 4-letter commands. Would
> that work for you?
> >
> > -Flavio
> >
> >> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com> wrote:
> >>
> >> Hi,
> >> is there any way to see in JMX which is the leader of a ZooKeeper
> cluster?
> >>
> >> My problem is: given access to any of the nodes of the cluster I want to
> >> know from JMX which is the current leader.
> >> It seems to me that this information is not available, you can know
> only if
> >> the local node is Leader or Follower.
> >>
> >> Cheers
> >> Enrico
> >
>
>
Re: Discover LEADER from JMX
Posted by Ansel Zandegran <An...@infor.com>.
Hi,
That is possible with 4 letter commands. We are using it now. In 3.5.x it is going to be removed in favour of admin server (embedded web server).
We are running in an environment where it’s not possible to run JMX or embedded web servers.
So I am wondering if there is another way? It would be nice to have this info as a znode.
Best regards,
Ansel
> On 8 May 2018, at 09:55, Flavio Junqueira <fp...@apache.org> wrote:
>
> Hi Enrico,
>
> You can determine the state of a server it via 4-letter commands. Would that work for you?
>
> -Flavio
>
>> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com> wrote:
>>
>> Hi,
>> is there any way to see in JMX which is the leader of a ZooKeeper cluster?
>>
>> My problem is: given access to any of the nodes of the cluster I want to
>> know from JMX which is the current leader.
>> It seems to me that this information is not available, you can know only if
>> the local node is Leader or Follower.
>>
>> Cheers
>> Enrico
>
Re: Discover LEADER from JMX
Posted by Flavio Junqueira <fp...@apache.org>.
Hi Enrico,
You can determine the state of a server it via 4-letter commands. Would that work for you?
-Flavio
> On 8 May 2018, at 09:09, Enrico Olivelli <eo...@gmail.com> wrote:
>
> Hi,
> is there any way to see in JMX which is the leader of a ZooKeeper cluster?
>
> My problem is: given access to any of the nodes of the cluster I want to
> know from JMX which is the current leader.
> It seems to me that this information is not available, you can know only if
> the local node is Leader or Follower.
>
> Cheers
> Enrico