[ZOOKEEPER-344] doIO in NioServerCnxn: Exception causing close of session : cause is "read error"

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 3.1.0
• Fix Version/s: 3.2.0
• Component/s: java client, server

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

• Hadoop Flags: Reviewed
• Assignee: Patrick D. Hunt
• Reporter: bryan thompson
• Created: 18/Mar/09 18:45
• Updated: 08/Jul/09 20:24
• Resolved: 06/May/09 17:04

Description

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