[jira] [Commented] (ZOOKEEPER-1936) Server exits when unable to create data directory due to race

["Chris Nauroth (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1936?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15505015#comment-15505015 ] 

Chris Nauroth commented on ZOOKEEPER-1936:
------------------------------------------

This patch has been stalled, because there is no easy way to write a unit test for it, and no one has been able to produce a consistent repro in a live environment.

I have good news.  I was able to find a consistent repro with an environment that could reproduce the problem in approximately 80% of ZooKeeper server starts.  FWIW, the OS was SUSE11sp3, and it was running ZooKeeper 3.4.6.  I applied the v3 patch, deployed it in this environment, and we could no longer repro.

Based on successful manual testing, I am now +1 to commit patch v4 to trunk and branch-3.5, and commit patch v3 to branch-3.4.  I will wait until later in the week in case other committers who have been watching the issue would like to discuss further.

> Server exits when unable to create data directory due to race 
> --------------------------------------------------------------
>
>                 Key: ZOOKEEPER-1936
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1936
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: server
>    Affects Versions: 3.4.6, 3.5.0
>            Reporter: Harald Musum
>            Assignee: Andrew Purtell
>            Priority: Minor
>         Attachments: ZOOKEEPER-1936.patch, ZOOKEEPER-1936.v2.patch, ZOOKEEPER-1936.v3.patch, ZOOKEEPER-1936.v3.patch, ZOOKEEPER-1936.v4.patch
>
>
> We sometime see issues with ZooKeeper server not starting and seeing this error in the log:
> [2014-05-27 09:29:48.248] ERROR   : -               
> .org.apache.zookeeper.server.ZooKeeperServerMain    Unexpected exception,
> exiting abnormally\nexception=\njava.io.IOException: Unable to create data
> directory /home/y/var/zookeeper/version-2\n\tat
> org.apache.zookeeper.server.persistence.FileTxnSnapLog.<init>(FileTxnSnapLog.java:85)\n\tat
> org.apache.zookeeper.server.ZooKeeperServerMain.runFromConfig(ZooKeeperServerMain.java:103)\n\tat
> org.apache.zookeeper.server.ZooKeeperServerMain.initializeAndRun(ZooKeeperServerMain.java:86)\n\tat
> org.apache.zookeeper.server.ZooKeeperServerMain.main(ZooKeeperServerMain.java:52)\n\tat
> org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:116)\n\tat
> org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78)\n\t
> [...]
> Stack trace from JVM gives this:
> "PurgeTask" daemon prio=10 tid=0x000000000201d000 nid=0x1727 runnable
> [0x00007f55d7dc7000]
>    java.lang.Thread.State: RUNNABLE
>     at java.io.UnixFileSystem.createDirectory(Native Method)
>     at java.io.File.mkdir(File.java:1310)
>     at java.io.File.mkdirs(File.java:1337)
>     at
> org.apache.zookeeper.server.persistence.FileTxnSnapLog.<init>(FileTxnSnapLog.java:84)
>     at org.apache.zookeeper.server.PurgeTxnLog.purge(PurgeTxnLog.java:68)
>     at
> org.apache.zookeeper.server.DatadirCleanupManager$PurgeTask.run(DatadirCleanupManager.java:140)
>     at java.util.TimerThread.mainLoop(Timer.java:555)
>     at java.util.TimerThread.run(Timer.java:505)
> "zookeeper server" prio=10 tid=0x00000000027df800 nid=0x1715 runnable
> [0x00007f55d7ed8000]
>    java.lang.Thread.State: RUNNABLE
>     at java.io.UnixFileSystem.createDirectory(Native Method)
>     at java.io.File.mkdir(File.java:1310)
>     at java.io.File.mkdirs(File.java:1337)
>     at
> org.apache.zookeeper.server.persistence.FileTxnSnapLog.<init>(FileTxnSnapLog.java:84)
>     at
> org.apache.zookeeper.server.ZooKeeperServerMain.runFromConfig(ZooKeeperServerMain.java:103)
>     at
> org.apache.zookeeper.server.ZooKeeperServerMain.initializeAndRun(ZooKeeperServerMain.java:86)
>     at
> org.apache.zookeeper.server.ZooKeeperServerMain.main(ZooKeeperServerMain.java:52)
>     at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:116)
>     at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78)
> [...]
> So it seems that when autopurge is used (as it is in our case), it might happen at the same time as starting the server itself. In FileTxnSnapLog() it will check if the directory exists and create it if not. These two tasks do this at the same time, and mkdir fails and server exits the JVM.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)