kafka-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Michael G. Noll" <mich...@michael-noll.com>
Subject Re: LeaderNotAvailableException in 0.8.1.1
Date Wed, 11 Jun 2014 20:40:32 GMT
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.


Mime
View raw message