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https://issues.apache.org/jira/browse/HBASE-7728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13569989#comment-13569989
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Anoop Sam John commented on HBASE-7728:
---------------------------------------
So in such a case we need to distinguish clearly that an Exception in flush or
sync is due to log roll. Now this is not this way.
In this defect case also an IOE has happened while flush but rolling of the log
and new writer creation was not happened by that time. (A rolling was in
progress but it has not reached till the point of creating new writer)
> 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-simplified.txt, 7728-0.94.txt,
> 7728-0.94-v2.txt, 7728-suggest-0.96.txt, 7728-suggest.txt, 7728-v1.txt,
> 7728-v2.txt, 7728-v3.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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