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From "bryan thompson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (ZOOKEEPER-344) doIO in NioServerCnxn: Exception causing close of session : cause is "read error"
Date Thu, 02 Apr 2009 21:17:12 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695136#action_12695136
] 

bryan thompson commented on ZOOKEEPER-344:
------------------------------------------

I am not sure how to boil this down into a problem which can be run on a single machine. 
This is a distributed database benchmark.  The problem shows up when the cluster is under
load.  How would I go about isolating that further outside of writing stress tests for zookeeper?

If this is indeed a zookeeper bug and you have some idea of the possible issues involved,
then perhaps you can suggest some additional instrumentation of zookeeper and I could run
against a version with more instrumentation which might reveal something?

Thanks,

-bryan


> doIO in NioServerCnxn: Exception causing close of session : cause is "read error"
> ---------------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-344
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-344
>             Project: Zookeeper
>          Issue Type: Bug
>          Components: java client, server
>    Affects Versions: 3.1.0
>         Environment: jdk1.6.0_07
> Linux blade2 2.6.27.7-134.fc10.x86_64 #1 SMP Mon Dec 1 22:21:35 EST 2008 x86_64 x86_64
x86_64 GNU/Linux
>            Reporter: bryan thompson
>             Fix For: 3.2.0
>
>
> I have been having a problem with zookeeper 3.0.1 and now with 3.1.0 where I see a lot
of expired sessions.  I am using a 16 node cluster which is all on the same local network.
 There is a single zookeeper instance (these are benchmarking runs).
> The problem appears to be correlated with either run time or system load.\
> Personally I think that it is system load because I have session session expired events
under a Windows platform running zookeeper and the application (i.e., everthing is local)
when the application load suddenly spikes.  To me this suggests that the client is not able
to renew (ping) the zookeeper service in a timely manner and is expired.  But the log messages
below with the "read error" suggest that maybe there is something else going on?
> Zookeeper Configuration
> #Wed Mar 18 12:41:05 GMT-05:00 2009
> clientPort=2181
> dataDir=/var/bigdata/benchmark/zookeeper/1
> syncLimit=2
> dataLogDir=/var/bigdata/benchmark/zookeeper/1
> tickTime=2000
> Some representative log messages are below.
> Client side messages (from our app)
> ERROR [main-EventThread] com.bigdata.zookeeper.ZLockImpl$ZLockWatcher.process(ZLockImpl.java:400)
2009-03-18 13:35:40,335 - Session expired: WatchedEvent: Server state change. New state: Expired
: zpath=/benchmark/jobs/com.bigdata.service.jini.benchmark.ThroughputMaster/test_1/client1160/locknode
> ERROR [main-EventThread] com.bigdata.zookeeper.ZLockImpl$ZLockWatcher.process(ZLockImpl.java:400)
2009-03-18 13:35:40,335 - Session expired: WatchedEvent: Server state change. New state: Expired
: zpath=/benchmark/jobs/com.bigdata.service.jini.benchmark.ThroughputMaster/test_1/client1356/locknode
> Server side messages:
>  WARN [NIOServerCxn.Factory:2181] org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:417)
2009-03-18 13:06:57,252 - Exception causing close of session 0x1201aac14300022 due to java.io.IOException:
Read error
>  WARN [NIOServerCxn.Factory:2181] org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:417)
2009-03-18 13:06:58,198 - Exception causing close of session 0x1201aac1430000f due to java.io.IOException:
Read error

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