Have you given Kafka some time to re-elect a new leader for the "missing" partition when you re-try steps 1-5?
See here: > If you do, you should be able to go through steps > 1-8 without seeing LeaderNotAvailableExceptions (you may need to give > Kafka some time to re-elect the remaining, second broker as the new > leader for the first broker's partitions though). Best, Michael On 06/12/2014 08:43 PM, Prakash Gowri Shankor wrote: > So if we go back to the 2 broker case, I tried your suggestion with > replication-factor 2 > > ./kafka-topics.sh --topic test2 --create --partitions 3 --zookeeper > localhost:2181 --replication-factor > > When i repeat steps 1-5 i still see the exception. When i go to step 8 ( > back to 2 brokers ), I dont see it. > Here is my topic description: > > ./kafka-topics.sh --describe --topic test2 --zookeeper localhost:2181 > > Topic:test2 PartitionCount:3 ReplicationFactor:2 Configs: > > Topic: test2 Partition: 0 Leader: 1 Replicas: 1,0 Isr: 1,0 > > Topic: test2 Partition: 1 Leader: 0 Replicas: 0,1 Isr: 0,1 > > Topic: test2 Partition: 2 Leader: 1 Replicas: 1,0 Isr: 1,0 > > > On Wed, Jun 11, 2014 at 3:20 PM, Michael G. Noll < > michael+st...@michael-noll.com> wrote: > >> In your second case (1-broker cluster and putting your laptop to sleep) >> these exceptions should be transient and disappear after a while. >> >> In the logs you should see ZK session expirations (hence the >> initial/transient exceptions, which in this case are expected and ok), >> followed by new ZK sessions being established. >> >> So this case is (should?) be very different from your case number 1. >> >> --Michael >> >> >>> On 11.06.2014, at 23:13, Prakash Gowri Shankor < >> prakash.shan...@gmail.com> wrote: >>> >>> Thanks for your response Michael. >>> >>> In step 3, I am actually stopping the entire cluster and restarting it >>> without the 2nd broker. But I see your point. When i look in >>> /tmp/kafka-logs-2 ( which is the log dir for the 2nd broker ) I see it >>> holds test2-1 ( ie 1st partition of test2 topic ). >>> For /tmp/kafka-logs ( which is the log dir for the first broker ) I see >> it >>> holds test2-0 and test2-2 ( 0th and 2nd partition of test2 topic ). >>> So it would seem that kafka is missing the leader for partition 1 and >> hence >>> throwing the exception on the producer side. >>> Let me try your replication suggestion. >>> >>> While all of the above might explain the exception in the case of 2 >>> brokers, there are still times when I see it with just a single broker. >>> In this case, I start from a normal working cluster with 1 broker only. >>> Then I either put my machine into sleep/hibernation. On wake, I do >> shutdown >>> the cluster ( for sanity ) and restart. >>> On restart, I start seeing this exception. In this case i only have one >>> broker. I still create the topic the way i described earlier. >>> I understand this is not the ideal production topology, but its annoying >> to >>> see it during development. >>> >>> Thanks >>> >>> >>> On Wed, Jun 11, 2014 at 1:40 PM, Michael G. Noll < >> mich...@michael-noll.com> >>> wrote: >>> >>>> Prakash, >>>> >>>> you are configure the topic with a replication factor of only 1, i.e. no >>>> additional replica beyond "the original one". This replication setting >>>> of 1 means that only one of the two brokers will ever host the (single) >>>> replica -- which is implied to also be the leader in-sync replica -- of >>>> a given partition. >>>> >>>> In step 3 you are disabling one of the two brokers. Because this >>>> stopped broker is the only broker that hosts one or more of the 3 >>>> partitions you configured (I can't tell which partition(s) it is, but >>>> you can find out by --describe'ing the topic), your Kafka cluster -- >>>> which is now running in degraded state -- will miss the leader of those >>>> affected partitions. And because you set the replication factor to 1, >>>> the remaining, second broker will not and will never take over the >>>> leadership of those partitions from the stopped broker. Hence you will >>>> keep getting the LeaderNotAvailableException's until you restart the >>>> stopped broker in step 7. >>>> >>>> So to me it looks as if the behavior of Kafka is actually correct and as >>>> expected. >>>> >>>> If you want to "rectify" your test setup, try increasing the replication >>>> factor from 1 to 2. If you do, you should be able to go through steps >>>> 1-8 without seeing LeaderNotAvailableExceptions (you may need to give >>>> Kafka some time to re-elect the remaining, second broker as the new >>>> leader for the first broker's partitions though). >>>> >>>> Hope this helps, >>>> Michael >>>> >>>> >>>> >>>>> On 06/11/2014 07:49 PM, Prakash Gowri Shankor wrote: >>>>> yes, >>>>> here are the steps: >>>>> >>>>> Create topic as : ./kafka-topics.sh --topic test2 --create >>>> --partitions 3 >>>>> --zookeeper localhost:2181 --replication-factor 1 >>>>> >>>>> 1) Start cluster with 2 brokers, 3 consumers. >>>>> 2) Dont start any producer >>>>> 3) Shutdown cluster and disable one broker from starting >>>>> 4) restart cluster with 1 broker, 3 consumers >>>>> 5) Start producer and send messages. I see this exception >>>>> 6) Shutdown cluster. >>>>> 7) Enable 2nd broker. >>>>> 8) Restart cluster with 2 brokers, 3 consumer and the one producer and >>>> send >>>>> messages. Now I dont see the exception. >>>> >>>> >> >
