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https://issues.apache.org/jira/browse/HBASE-7728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568813#comment-13568813
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Lars Hofhansl commented on HBASE-7728:
--------------------------------------
Am still not 100% sold that we need to set the writer to null upon close and
add the null check everywhere in syncer().
The change of the locking order should be enough. If not, please explain it to
me :)
> deadlock occurs between hlog roller and hlog syncer
> ---------------------------------------------------
>
> Key: HBASE-7728
> URL: https://issues.apache.org/jira/browse/HBASE-7728
> Project: HBase
> Issue Type: Bug
> Components: wal
> Affects Versions: 0.94.2
> Environment: Linux 2.6.18-164.el5 x86_64 GNU/Linux
> Reporter: Wang Qiang
> Assignee: Ted Yu
> Priority: Blocker
> Fix For: 0.96.0, 0.94.5
>
> Attachments: 7728-0.94.txt, 7728-suggest-0.96.txt, 7728-suggest.txt,
> 7728-v1.txt, 7728-v2.txt, 7728-v3.txt, 7728-v4.txt, 7728-v4.txt
>
>
> the hlog roller thread and hlog syncer thread may occur dead lock with the
> 'flushLock' and 'updateLock', and then cause all 'IPC Server handler' thread
> blocked on hlog append. the jstack info is as follow :
> "regionserver60020.logRoller":
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1305)
> - waiting to lock <0x000000067bf88d58> (a java.lang.Object)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1283)
> at org.apache.hadoop.hbase.regionserver.wal.HLog.sync(HLog.java:1456)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.cleanupCurrentWriter(HLog.java:876)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.rollWriter(HLog.java:657)
> - locked <0x000000067d54ace0> (a java.lang.Object)
> at
> org.apache.hadoop.hbase.regionserver.LogRoller.run(LogRoller.java:94)
> at java.lang.Thread.run(Thread.java:662)
> "regionserver60020.logSyncer":
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1314)
> - waiting to lock <0x000000067d54ace0> (a java.lang.Object)
> - locked <0x000000067bf88d58> (a java.lang.Object)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog.syncer(HLog.java:1283)
> at org.apache.hadoop.hbase.regionserver.wal.HLog.sync(HLog.java:1456)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLog$LogSyncer.run(HLog.java:1235)
> at java.lang.Thread.run(Thread.java:662)
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