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. >> >>
