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Posted to users@kafka.apache.org by Cosmin Marginean <co...@gmail.com> on 2016/01/08 12:20:38 UTC
Leader not available (initially)
Hi guys
I’ve been seeing this in our logs a few times, when initially bootstrapping the system.
WARN 2016-01-08 10:59:24,232 [pool-3-thread-11] [none] o.a.kafka.clients.NetworkClient: Error while fetching metadata with correlation id 3 : {mytopic=LEADER_NOT_AVAILABLE}
It doesn’t seem to break anything, and it seems to be related to the fact that we do processing on the topic right after creating it. Below is our workflow (roughly)
* Create topic (using AdminUtils)
* Register some tens of consumers
* Send some messages with a producer
I’d like to know if this is something to worry about (the warning that is) or if it’s something we should investigate further.
Thank you
Cosmin
Re: Leader not available (initially)
Posted by Cosmin Marginean <co...@gmail.com>.
Hi yes, was actually just writing a reply to that :)
Found the rest of the context: "Alternatively, instead of manually creating topics you can also configure your brokers to auto-create topics when a non-existent topic is published to.”
I tried this: commented out my code that creates the topic and just throw something at the publisher. So basically:
1. Publisher.send
2. Consumer.register
The warning is still there (as per Dana’s comment, is expected), but no messages are being consumed.
However, this is less material, as it seems to be a *different* problem altogether.
My concern now is what happens if the topic is freshly created (manually or not) and hundreds of messages are being published (and that warning is being displayed).
I also saw things like "A side note is that you may want to use waitUntil to check the topic is
created after using AdminUtils.createTopic since it is async.” (from here http://mail-archives.apache.org/mod_mbox/kafka-users/201410.mbox/%3CCAHwHRrUUAuazRtjdzr6geeG6D0hhPeneAU412N-C7Xk3UwLbGA@mail.gmail.com%3E)
but I can’t find anything like waitUntil in that API
Thank you again for your support
Cos
On Friday, 8 January 2016 at 17:19, Marko Bonaći wrote:
> I think that the attempt to write a message to a non-existent topic creates
> that topic (when auto.create is set to true).
> If it's set to false you get back error.
> Have you tried that?
>
> Marko Bonaći
> Monitoring | Alerting | Anomaly Detection | Centralized Log Management
> Solr & Elasticsearch Support
> Sematext <http://sematext.com/> | Contact
> <http://sematext.com/about/contact.html>
>
> On Fri, Jan 8, 2016 at 5:51 PM, Cosmin Marginean <cosmarginean@gmail.com (mailto:cosmarginean@gmail.com)>
> wrote:
>
> > Hi Dana
> >
> > I am actually creating the topic manually from our code. This is mainly
> > because I couldn’t tell from the documentation when exactly is the topic
> > auto-created - maybe you can shed some light on that.
> >
> > The docs (http://kafka.apache.org/documentation.html) only mention
> > auto.create.topics.enable Enable auto creation of topic on the server
> > which is a bit without context.
> >
> > Either way (automated or not), it is crucial for us to know if the message
> > actually gets sent. The problem is we need to get the producer to send some
> > messages as soon as the system bootstraps (and potentially creates the
> > topic). So is it possible to know (listener, etc) on the producer side when
> > the topic is “operational”, or at least to handle a specific exception?
> >
> > Or is it a case where the producer will buffer these on the client side?
> >
> > Thanks
> > Cos
> >
> >
> >
> > On Friday, 8 January 2016 at 16:45, Dana Powers wrote:
> >
> > > That is expected when a topic is first created. Once the topic and all
> > > partitions are initialized, the leader(s) will be available and you can
> > > produce messages.
> > >
> > > Note that if you disable topic auto creation, you should get an
> > > UnknownTopicOrPartitionError, and you would need to create the topic
> > > manually.
> > >
> > > -Dana
> > > On Jan 8, 2016 03:20, "Cosmin Marginean" <cosmarginean@gmail.com (mailto:cosmarginean@gmail.com)
> > >
> >
> > (mailto:cosmarginean@gmail.com)> wrote:
> > >
> > > > Hi guys
> > > >
> > > > I’ve been seeing this in our logs a few times, when initially
> > > > bootstrapping the system.
> > > >
> > > > WARN 2016-01-08 10:59:24,232 [pool-3-thread-11] [none]
> > > > o.a.kafka.clients.NetworkClient: Error while fetching metadata with
> > > > correlation id 3 : {mytopic=LEADER_NOT_AVAILABLE}
> > > >
> > > > It doesn’t seem to break anything, and it seems to be related to the
> > fact
> > > > that we do processing on the topic right after creating it. Below is
> > >
> >
> > our
> > > > workflow (roughly)
> > > > * Create topic (using AdminUtils)
> > > > * Register some tens of consumers
> > > > * Send some messages with a producer
> > > >
> > > > I’d like to know if this is something to worry about (the warning that
> > is)
> > > > or if it’s something we should investigate further.
> > > >
> > > > Thank you
> > > > Cosmin
> > > >
> > >
> >
> >
>
>
>
Re: Leader not available (initially)
Posted by Marko Bonaći <ma...@sematext.com>.
I think that the attempt to write a message to a non-existent topic creates
that topic (when auto.create is set to true).
If it's set to false you get back error.
Have you tried that?
Marko Bonaći
Monitoring | Alerting | Anomaly Detection | Centralized Log Management
Solr & Elasticsearch Support
Sematext <http://sematext.com/> | Contact
<http://sematext.com/about/contact.html>
On Fri, Jan 8, 2016 at 5:51 PM, Cosmin Marginean <co...@gmail.com>
wrote:
> Hi Dana
>
> I am actually creating the topic manually from our code. This is mainly
> because I couldn’t tell from the documentation when exactly is the topic
> auto-created - maybe you can shed some light on that.
>
> The docs (http://kafka.apache.org/documentation.html) only mention
> auto.create.topics.enable Enable auto creation of topic on the server
> which is a bit without context.
>
> Either way (automated or not), it is crucial for us to know if the message
> actually gets sent. The problem is we need to get the producer to send some
> messages as soon as the system bootstraps (and potentially creates the
> topic). So is it possible to know (listener, etc) on the producer side when
> the topic is “operational”, or at least to handle a specific exception?
>
> Or is it a case where the producer will buffer these on the client side?
>
> Thanks
> Cos
>
>
>
> On Friday, 8 January 2016 at 16:45, Dana Powers wrote:
>
> > That is expected when a topic is first created. Once the topic and all
> > partitions are initialized, the leader(s) will be available and you can
> > produce messages.
> >
> > Note that if you disable topic auto creation, you should get an
> > UnknownTopicOrPartitionError, and you would need to create the topic
> > manually.
> >
> > -Dana
> > On Jan 8, 2016 03:20, "Cosmin Marginean" <cosmarginean@gmail.com
> (mailto:cosmarginean@gmail.com)> wrote:
> >
> > > Hi guys
> > >
> > > I’ve been seeing this in our logs a few times, when initially
> > > bootstrapping the system.
> > >
> > > WARN 2016-01-08 10:59:24,232 [pool-3-thread-11] [none]
> > > o.a.kafka.clients.NetworkClient: Error while fetching metadata with
> > > correlation id 3 : {mytopic=LEADER_NOT_AVAILABLE}
> > >
> > > It doesn’t seem to break anything, and it seems to be related to the
> fact
> > > that we do processing on the topic right after creating it. Below is
> our
> > > workflow (roughly)
> > > * Create topic (using AdminUtils)
> > > * Register some tens of consumers
> > > * Send some messages with a producer
> > >
> > > I’d like to know if this is something to worry about (the warning that
> is)
> > > or if it’s something we should investigate further.
> > >
> > > Thank you
> > > Cosmin
> > >
> >
> >
> >
>
>
>
Re: Leader not available (initially)
Posted by Cosmin Marginean <co...@gmail.com>.
Hi Dana
I am actually creating the topic manually from our code. This is mainly because I couldn’t tell from the documentation when exactly is the topic auto-created - maybe you can shed some light on that.
The docs (http://kafka.apache.org/documentation.html) only mention
auto.create.topics.enable Enable auto creation of topic on the server
which is a bit without context.
Either way (automated or not), it is crucial for us to know if the message actually gets sent. The problem is we need to get the producer to send some messages as soon as the system bootstraps (and potentially creates the topic). So is it possible to know (listener, etc) on the producer side when the topic is “operational”, or at least to handle a specific exception?
Or is it a case where the producer will buffer these on the client side?
Thanks
Cos
On Friday, 8 January 2016 at 16:45, Dana Powers wrote:
> That is expected when a topic is first created. Once the topic and all
> partitions are initialized, the leader(s) will be available and you can
> produce messages.
>
> Note that if you disable topic auto creation, you should get an
> UnknownTopicOrPartitionError, and you would need to create the topic
> manually.
>
> -Dana
> On Jan 8, 2016 03:20, "Cosmin Marginean" <cosmarginean@gmail.com (mailto:cosmarginean@gmail.com)> wrote:
>
> > Hi guys
> >
> > I’ve been seeing this in our logs a few times, when initially
> > bootstrapping the system.
> >
> > WARN 2016-01-08 10:59:24,232 [pool-3-thread-11] [none]
> > o.a.kafka.clients.NetworkClient: Error while fetching metadata with
> > correlation id 3 : {mytopic=LEADER_NOT_AVAILABLE}
> >
> > It doesn’t seem to break anything, and it seems to be related to the fact
> > that we do processing on the topic right after creating it. Below is our
> > workflow (roughly)
> > * Create topic (using AdminUtils)
> > * Register some tens of consumers
> > * Send some messages with a producer
> >
> > I’d like to know if this is something to worry about (the warning that is)
> > or if it’s something we should investigate further.
> >
> > Thank you
> > Cosmin
> >
>
>
>
Re: Leader not available (initially)
Posted by Dana Powers <da...@gmail.com>.
That is expected when a topic is first created. Once the topic and all
partitions are initialized, the leader(s) will be available and you can
produce messages.
Note that if you disable topic auto creation, you should get an
UnknownTopicOrPartitionError, and you would need to create the topic
manually.
-Dana
On Jan 8, 2016 03:20, "Cosmin Marginean" <co...@gmail.com> wrote:
> Hi guys
>
> I’ve been seeing this in our logs a few times, when initially
> bootstrapping the system.
>
> WARN 2016-01-08 10:59:24,232 [pool-3-thread-11] [none]
> o.a.kafka.clients.NetworkClient: Error while fetching metadata with
> correlation id 3 : {mytopic=LEADER_NOT_AVAILABLE}
>
> It doesn’t seem to break anything, and it seems to be related to the fact
> that we do processing on the topic right after creating it. Below is our
> workflow (roughly)
> * Create topic (using AdminUtils)
> * Register some tens of consumers
> * Send some messages with a producer
>
> I’d like to know if this is something to worry about (the warning that is)
> or if it’s something we should investigate further.
>
> Thank you
> Cosmin
>
>