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. > >> > >> >
