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From Anand Parthasarathy <anpar...@avinetworks.com>
Subject Re: Zookeeper leader election takes a long time.
Date Sat, 08 Oct 2016 17:05:48 GMT
Hi Flavio,

I have attached the logs from node 1 and node 3. Node 2 was powered off
around 10-03 12:36. Leader election kept going until 10-03 15:57:16 when it
finally converged.

Thanks,
Anand.

On Sat, Oct 8, 2016 at 7:55 AM, Flavio Junqueira <fpj@apache.org> wrote:

> Hi Anand,
>
> I don't understand whether 1 and 3 were able or even trying to connect to
> each other. They should be able to elect a leader between them and make
> progress. You might want to upload logs and let us know.
>
> -Flavio
>
> > On 08 Oct 2016, at 02:11, Anand Parthasarathy <anpartha@avinetworks.com>
> wrote:
> >
> > Hi,
> >
> > We are currently using zookeeper 3.4.6 version and use a 3 node solution
> in
> > our system. We see that occasionally, when a node is powered off (in this
> > instance, it was actually a leader node), the remaining two nodes do not
> > form a quorum for a really long time. Looking at the logs, it appears the
> > sequence is as follows:
> > - Node 2 is the zookeeper leader
> > - Node 2 is powered off
> > - Node 1 and Node 3 recognize and start the election
> > - Node 3 times out after initLimit * tickTime with "Timeout while waiting
> > for quorum" for Round N
> > - Node 1 times out after initLimit * tickTime with "Exception while
> trying
> > to follow leader" for Round N+1 at the same time.
> > - And the process continues where N is sequentially incrementing.
> > - This happens for a long time.
> > - In one instance, we used tickTime=5000 and initLimit=20 and it took
> > around 3.5 hours to converge.
> > - In a given round, Node 1 will try connecting to Node 2, gets connection
> > refused waits for notification timeout which increases by 2 every
> iteration
> > until it hits the initLimit. Connection Refused is because the node 2
> comes
> > up after reboot, but zookeeper process is not started (due to a different
> > failure).
> >
> > It looks similar to ZOOKEEPER-2164 but there it is a connection timeout
> > where Node 2 is not reachable.
> >
> > Could you pls. share if you have seen this issue and if so, what is the
> > workaround that can be employed in 3.4.6.
> >
> > Thanks,
> > Anand.
>
>

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