Transient rebalance failures are ok. However, it's important that the last rebalance in a sequence succeeds. Otherwise, some of the partitions will not be consumed by any consumers.
Thanks, Jun On Fri, Nov 29, 2013 at 10:44 AM, Yu, Libo <libo...@citi.com> wrote: > You are right, Joe. I checked our brokers' log. We have three brokers. All > of them failed to connect to zk at some point. > So they were offline and later reregistered themselves with the zk. I > don't know how many rebalance should be > triggered in that case. There is only one exception found in consumer's > log. My question is whether users need to do > anything to handle ConsumerRebalanceFailedException. > > This is from consumer log: > > [28/11/13 16:38:56:056 PM EST] 102 ERROR > consumer.ZookeeperConsumerConnector: [xxxxxxxxxx > ], error during syncedRebalance > kafka.common.ConsumerRebalanceFailedException: xxxxxxxxx can't rebalance > after 4 retries > at > kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener.syncedReb > alance(ZookeeperConsumerConnector.scala:397) > at > kafka.consumer.ZookeeperConsumerConnector$ZKRebalancerListener$$anon$1.r > un(ZookeeperConsumerConnector.scala:326) > > Regards, > > Libo > > > -----Original Message----- > From: Joe Stein [mailto:joe.st...@stealth.ly] > Sent: Friday, November 29, 2013 11:57 AM > To: users@kafka.apache.org > Subject: Re: ConsumerRebalanceFailedException > > What is the full stack trace? if you see "can't rebalance after 4 retries" > then likely the problem is the broker is down or not available > > /******************************************* > Joe Stein > Founder, Principal Consultant > Big Data Open Source Security LLC > http://www.stealth.ly > Twitter: @allthingshadoop <http://www.twitter.com/allthingshadoop> > ********************************************/ > > > On Fri, Nov 29, 2013 at 11:31 AM, Yu, Libo <libo...@citi.com> wrote: > > > We found our consumer stopped working after this exception occurred. > > Can the consumer recover from such an exception? > > > > Regards, > > > > Libo > > > > > > -----Original Message----- > > From: Florin Trofin [mailto:ftro...@adobe.com] > > Sent: Tuesday, July 16, 2013 4:20 PM > > To: users@kafka.apache.org > > Subject: Re: ConsumerRebalanceFailedException > > > > Yes, I think these are two separate issues. > > > > F. > > > > On 7/16/13 11:32 AM, "Joel Koshy" <jjkosh...@gmail.com> wrote: > > > > >From a user's perspective, ConsumerRebalanceException is a bit > > >cryptic -I think the other thread was to provide a more informative > > >message and also be able to recover when a broker does come up (fixed > > >in KAFKA-969). > > > > > >Thanks, > > > > > >Joel > > > > > >On Tue, Jul 16, 2013 at 11:04 AM, Vaibhav Puranik > > ><vpura...@gmail.com> > > >wrote: > > >> Thank you Joel. > > >> > > >> In a different but related thread, somebody is asking to rename the > > >> exception as NoBrokerAvailableExcption. But given the description > > >> above, the exception seems to be named appropriately. > > >> > > >> Regards, > > >> Vaibhav > > >> > > >> > > >> On Tue, Jul 16, 2013 at 12:05 AM, Joel Koshy <jjkosh...@gmail.com> > > >>wrote: > > >> > > >>> Yes - rebalance => consumers trying to coordinate through ZK. > > >>> Rebalances can happen when one or more of the following happen: > > >>> - a consumed topic partition appears or disappears - i.e., if a > > >>> broker comes or goes. > > >>> - a consumer instance in the group comes or goes "goes" could also > > >>> be triggered by session expirations in zookeeper - typically > > >>> caused by client-side GC or flaky connections to zookeeper. > > >>> > > >>> On Mon, Jul 15, 2013 at 10:15 AM, Vaibhav Puranik > > >>> <vpura...@gmail.com> > > >>> wrote: > > >>> > Hi all, > > >>> > > > >>> > We have a small Kafka cluster (0.7.1 - 3 nodes) in EC2. The load > > >>> > is > > >>>about > > >>> > 200 million events per day, each being few kilobytes. We have a > > >>>single > > >>> node > > >>> > zookeeper. > > >>> > > > >>> > Yesterday suddenly our Kafka clients started throwing the > > >>> > following > > >>> > exception: > > >>> > java.lang.RuntimeException: > > >>> kafka.common.ConsumerRebalanceFailedException: > > >>> > > > >>>CONSUMER_GROUP_NAME_ip-00-00-00-00.ec2.internal-1373821190828-5f78e > > >>>9a > > >>>f > > >>> > can't rebalance after 4 retries > > >>> > at > > >>> > > > >>> > > >>>com.gumgum.kafka.consumer.KafkaTemplate.executeWithBatch(KafkaTempl > > >>>at > > >>>e.j > > >>>ava:59) > > >>> > at > > >>> > > > >>> > > >>>com.gumgum.storm.fileupload.GenericKafkaSpout.nextTuple(GenericKafk > > >>>aS > > >>>pou > > >>>t.java:73) > > >>> > at > > >>> > > > >>> > > >>>backtype.storm.daemon.executor$fn__3968$fn__4009$fn__4010.invoke(ex > > >>>ec > > >>>uto > > >>>r.clj:433) > > >>> > at > > >>> > backtype.storm.util$async_loop$fn__465.invoke(util.clj:377) > > >>> > > > >>> > None of the Kafka clients (ConsumerConenctor class) would start. > > >>> > They > > >>> would > > >>> > fail with the exception. > > >>> > > > >>> > We tried restarting the clilents, restarting the zookeeper as well. > > >>>But > > >>> > finally it all started working when we restarted all of our > > >>> > kafka > > >>> brokers. > > >>> > We didn't lose any data because producers (going directly to the > > >>>brokers > > >>> > through a load balancer) were working fine. > > >>> > > > >>> > I tried googling this issue and looks like lot of people have > > >>> > faced > > >>>it, > > >>> but > > >>> > couldn't get anything concrete. > > >>> > > > >>> > Given this, I have two questions: > > >>> > > > >>> > It will be nice if you can tell me why this can happen or point > > >>> > me > > >>>to a > > >>> > link where I can understand it better. What does Consumer > > >>> > Rebalancing > > >>> mean? > > >>> > Does that mean consumers are trying to coordinate amongst > > >>> > themselves > > >>> using > > >>> > Zookeeper? > > >>> > > > >>> > On a separate note, are there any JMX parameters I need to be > > >>>monitoring > > >>> to > > >>> > make sure that my kafka cluster is healthy? How can I keep watch > > >>> > on > > >>>my > > >>> > kafka cluster? > > >>> > > > >>> > Regards, > > >>> > Vaibhav Puranik > > >>> > GumGum > > >>> > > > > >
