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From "Mahadev konar (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 22:11:12 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695148#action_12695148
] 

Mahadev konar commented on ZOOKEEPER-344:
-----------------------------------------

brayn,
 the one thing you can do is run with tracefile option in the config. Please take a look at
http://hadoop.apache.org/zookeeper/docs/r3.1.1/zookeeperAdmin.html to see how to set up a
tracefile. The tracefile has logs of all the transactions that go though the server and all

the components of the server and helps in debugging problems such as these, where you can
point out which transaction got delayed and at what time and sometimes can point out
the reason why... 

> 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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