lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Per Steffensen (Created) (JIRA)" <>
Subject [jira] [Created] (SOLR-3274) ZooKeeper related SolrCloud problems
Date Mon, 26 Mar 2012 13:02:30 GMT
ZooKeeper related SolrCloud problems

                 Key: SOLR-3274
             Project: Solr
          Issue Type: Bug
          Components: SolrCloud
    Affects Versions: 4.0
         Environment: Any
            Reporter: Per Steffensen

Same setup as in SOLR-3273. Well if I have to tell the entire truth we have 7 Solr servers,
running 28 slices of the same collection (collA) - all slices have one replica (two shards
all in all - leader + replica) - 56 cores all in all (8 shards on each solr instance). But

Besides the problem reported in SOLR-3273, the system seems to run fine under high load for
several hours, but eventually errors like the ones shown below start to occur. I might be
wrong, but they all seem to indicate some kind of unstability in the collaboration between
Solr and ZooKeeper. I have to say that I havnt been there to check ZooKeeper "at the moment
where those exception occur", but basically I dont believe the exceptions occur because ZooKeeper
is not running stable - at least when I go and check ZooKeeper through other "channels" (e.g.
my eclipse ZK plugin) it is always accepting my connection and generally seems to be doing

Exception 1) Often the first error we see in solr.log is something like this
Mar 22, 2012 5:06:43 AM org.apache.solr.common.SolrException log
SEVERE: org.apache.solr.common.SolrException: Cannot talk to ZooKeeper - Updates are disabled.
        at org.apache.solr.update.processor.DistributedUpdateProcessor.zkCheck(
        at org.apache.solr.update.processor.DistributedUpdateProcessor.processAdd(
        at org.apache.solr.handler.XMLLoader.processUpdate(
        at org.apache.solr.handler.XMLLoader.load(
        at org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(
        at org.apache.solr.handler.RequestHandlerBase.handleRequest(
        at org.apache.solr.core.SolrCore.execute(
        at org.apache.solr.servlet.SolrDispatchFilter.execute(
        at org.apache.solr.servlet.SolrDispatchFilter.doFilter(
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(
        at org.mortbay.jetty.servlet.ServletHandler.handle(
        at org.mortbay.jetty.servlet.SessionHandler.handle(
        at org.mortbay.jetty.handler.ContextHandler.handle(
        at org.mortbay.jetty.webapp.WebAppContext.handle(
        at org.mortbay.jetty.handler.ContextHandlerCollection.handle(
        at org.mortbay.jetty.handler.HandlerCollection.handle(
        at org.mortbay.jetty.handler.HandlerWrapper.handle(
        at org.mortbay.jetty.Server.handle(
        at org.mortbay.jetty.HttpConnection.handleRequest(
        at org.mortbay.jetty.HttpConnection$RequestHandler.content(
        at org.mortbay.jetty.HttpParser.parseNext(
        at org.mortbay.jetty.HttpParser.parseAvailable(
        at org.mortbay.jetty.HttpConnection.handle(
        at org.mortbay.thread.QueuedThreadPool$
I believe this error basically occurs because SolrZkClient.isConnected reports false, which
means that its internal "keeper.getState" does not return ZooKeeper.States.CONNECTED. Im pretty
sure that it has been CONNECTED for a long time, since this error starts occuring after several
hours of processing without this problem showing. But why is it suddenly not connected anymore?!

Exception 2) We also see errors like the following, and if Im not mistaken, they start occuring
shortly after "Exception 1)" (above) shows for the fist time
Mar 22, 2012 5:07:26 AM org.apache.solr.common.SolrException log
SEVERE: org.apache.solr.common.SolrException: no servers hosting shard: 
        at org.apache.solr.handler.component.HttpShardHandler$
        at org.apache.solr.handler.component.HttpShardHandler$
        at java.util.concurrent.FutureTask$Sync.innerRun(
        at java.util.concurrent.Executors$
        at java.util.concurrent.FutureTask$Sync.innerRun(
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(
        at java.util.concurrent.ThreadPoolExecutor$
Please note that the exception says "no servers hosting shard: <blank>". Looking at
the code a "shard"-string was actually supposed to be written at <blank>.  Basically
this means that HttpShardHandler.submit was called with an empty "shard"-string parameter.
But who does this? CoreAdminHandler.handleDistribUrlAction or SearchHandler.handleRequestBody
or SyncStrategy or PeerSync or... I dont know, and maybe it is not that relevant, because
I guess they all get the "shard"-string from ZooKeeper. Again something pointing in the direction
of unstable collaboration between Solr and ZooKeeper.

Exception 3) We also see exceptions like this
Mar 25, 2012 3:05:38 PM$3 process
WARNING: ZooKeeper watch triggered, but Solr cannot talk to ZK
Mar 25, 2012 3:05:38 PM$1 process
org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode = Session expired
for /collections/collA/leader_elect/slice26/election
        at org.apache.zookeeper.KeeperException.create(
        at org.apache.zookeeper.KeeperException.create(
        at org.apache.zookeeper.ZooKeeper.getChildren(
        at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(
        at org.apache.zookeeper.ClientCnxn$

Maybe this will we usable for some bug-fixing or for making the code more stable. I know 4.0
is not stable/released yet, and that we therefore should expect this kind of errors at the
moment. So this is not negative criticism - just reporting of issues observed when using SolrCloud
features under high load for several days. Any feedback is more than welcome.

Regards, Per Steffensen

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:!default.jspa
For more information on JIRA, see:


To unsubscribe, e-mail:
For additional commands, e-mail:

View raw message