On 1/26/2015 2:26 PM, Vijay Sekhri wrote:
> Hi Erick,
> In solr.xml file I had zk timeout set to/ <int
> name="zkClientTimeout">${zkClientTimeout:450000}</int>/
> One thing that made a it a bit better now is the zk tick time and
> syncLimit settings. I set it to a higher value as below. This may not
> be advisable though.
>
> tickTime=30000
> initLimit=30
> syncLimit=20
>
> Now we observed that replicas do not go in recovery that often as
> before. In the whole cluster at a given time I would have a couple of
> replicas in recovery whereas earlier it were multiple replicas from
> every shard .
> On the wiki https://wiki.apache.org/solr/SolrCloudit says the "The
> maximum is 20 times the tickTime." in the FAQ so I decided to increase
> the tick time. Is this the correct approach ?
The default zkClientTimeout on recent Solr versions is 30 seconds, up
from 15 in slightly older releases.
Those values of 15 or 30 seconds are a REALLY long time in computer
terms, and if you are exceeding that timeout on a regular basis,
something is VERY wrong with your Solr install. Rather than take steps
to increase your timeout beyond the normal maximum of 40 seconds (20
times a tickTime of 2 seconds), figure out why you're exceeding that
timeout and fix the performance problem. The zkClientTimeout value that
you have set, 450 seconds, is seven and a half *MINUTES*. Nothing in
Solr should ever take that long.
"Not enough memory in the server" is by far the most common culprit for
performance issues. Garbage collection pauses are a close second.
I don't actually know this next part for sure, because I've never looked
into the code, but I believe that increasing the tickTime, especially to
a value 15 times higher than default, might make all zookeeper
operations a lot slower.
Thanks,
Shawn
