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Posted to issues@hbase.apache.org by "Jean-Daniel Cryans (JIRA)" <ji...@apache.org> on 2013/08/21 23:22:53 UTC
[jira] [Updated] (HBASE-7590) Add a costless notifications
mechanism from master to regionservers & clients
[ https://issues.apache.org/jira/browse/HBASE-7590?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jean-Daniel Cryans updated HBASE-7590:
--------------------------------------
Release Note:
This allows to setup a multicast connection between the master and the hbase clients. With the feature on, when a regionserver is marked as dead by the master, the master sends as well a multicast message that will make the hbase client to disconnect immediately from the dead server instead of waiting for a socket timeout. Specifically, this allows to set hbase.rpc.timeout to larger values (like 5 minutes) without impacting the MTTR: without this, even if the dead regionserver data is now available on another server, the client stays on the dead one, waiting for an answer that will never come. It's a multicast message, hence cheap, scalable, but unreliable. For this reason, the master sends the information 5 times, to allow the hbase client to miss a message. This feature is NOT activated by default. To activate it, add to your hbase-site.xml:
<property>
<name>hbase.status.publisher.class</name>
<value>org.apache.hadoop.hbase.master.ClusterStatusPublisher$MulticastPublisher</value>
</property>
<property>
<name>hbase.status.listener.class</name>
<value>org.apache.hadoop.hbase.client.ClusterStatusListener$MultiCastListener</value>
</property>
You can as well configure the ip address and port used with the following setting:
<property>
<name>hbase.status.multicast.address.ip</name>
<value>226.1.1.3</value>
</property>
<property>
<name>hbase.status.multicast.address.port</name>
<value>6100</value>
</property>
was:
This allows to setup a multicast connection between the master and the hbase clients. With the feature on, when a regionserver is marked as dead by the master, the master sends as well a multicast message that will make the hbase client to disconnect immediately from the dead server instead of waiting for a socket timeout. Specifically, this allows to set hbase.rpc.timeout to larger values (like 5 minutes) without impacting the MTTR: without this, even if the dead regionserver data is now available on another server, the client stays on the dead one, waiting for an answer that will never come. It's a multicast message, hence cheap, scalable, but unreliable. For this reason, the master sends the information 5 times, to allow the hbase client to miss a message. This feature is NOT activated by default. To activate it, add to your hbase-site.xml:
<property>
<name>hbase.status.publisher.class</name>
<value>org.apache.hadoop.hbase.master.ClusterStatusPublisher$MulticastPublisher</value>
</property>
<property>
<name>hbase.status.listener.class</name>
<value>org.apache.hadoop.hbase.client.ClusterStatusListener$MulticastListener</value>
</property>
You can as well configure the ip address and port used with the following setting:
<property>
<name>hbase.status.multicast.address.ip</name>
<value>226.1.1.3</value>
</property>
<property>
<name>hbase.status.multicast.address.port</name>
<value>6100</value>
</property>
I fixed the release note. It was not "MulticastListener" but "MultiCastListener" and "MulticastPublisher" does have a lower case. Consistency guys :)
> Add a costless notifications mechanism from master to regionservers & clients
> -----------------------------------------------------------------------------
>
> Key: HBASE-7590
> URL: https://issues.apache.org/jira/browse/HBASE-7590
> Project: HBase
> Issue Type: Bug
> Components: Client, master, regionserver
> Affects Versions: 0.95.2
> Reporter: Nicolas Liochon
> Assignee: Nicolas Liochon
> Fix For: 0.98.0, 0.95.0
>
> Attachments: 7590.inprogress.patch, 7590.v12.patch, 7590.v12.patch, 7590.v13.patch, 7590.v1.patch, 7590.v1-rebased.patch, 7590.v2.patch, 7590.v3.patch, 7590.v5.patch, 7590.v5.patch
>
>
> t would be very useful to add a mechanism to distribute some information to the clients and regionservers. Especially It would be useful to know globally (regionservers + clients apps) that some regionservers are dead. This would allow:
> - to lower the load on the system, without clients using staled information and going on dead machines
> - to make the recovery faster from a client point of view. It's common to use large timeouts on the client side, so the client may need a lot of time before declaring a region server dead and trying another one. If the client receives the information separatly about a region server states, it can take the right decision, and continue/stop to wait accordingly.
> We can also send more information, for example instructions like 'slow down' to instruct the client to increase the retries delay and so on.
> Technically, the master could send this information. To lower the load on the system, we should:
> - have a multicast communication (i.e. the master does not have to connect to all servers by tcp), with once packet every 10 seconds or so.
> - receivers should not depend on this: if the information is available great. If not, it should not break anything.
> - it should be optional.
> So at the end we would have a thread in the master sending a protobuf message about the dead servers on a multicast socket. If the socket is not configured, it does not do anything. On the client side, when we receive an information that a node is dead, we refresh the cache about it.
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