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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6318) SplitLogWorker exited due to ConcurrentModificationException
Date Tue, 03 Jul 2012 23:30:34 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13406167#comment-13406167
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Jimmy Xiang commented on HBASE-6318:
------------------------------------

Wrong patch name.

The map is a Collections.synchronzedMap.  So it protects race against getOutputCounts(), and
all other methods like put() and get() on this map.

The attached patch uses synchronizd on a strong consistent iterator.  There are not many threads
here.
So performance wise, it should be fine.

However, there is still possible leakage.  For example, some thread created a writer, right
before putting it to the map, it is blocked
because closeLogWriters() has the lock.  This writer will not be closed.

Probably it is better to fix the t.join() interruption, or the leakage is rare, and not a
big deal?

                
> SplitLogWorker exited due to ConcurrentModificationException
> ------------------------------------------------------------
>
>                 Key: HBASE-6318
>                 URL: https://issues.apache.org/jira/browse/HBASE-6318
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 0.96.0
>            Reporter: Jimmy Xiang
>         Attachments: 6138.patch, 6318-suggest.txt, 6318.log
>
>
> In playing with 0.96 code on a live cluster, found this issue:
> 2012-07-03 12:13:32,572 ERROR org.apache.hadoop.hbase.regionserver.SplitLogWorker: unexpected
error
> java.util.ConcurrentModificationException
>         at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1100)
>         at java.util.TreeMap$ValueIterator.next(TreeMap.java:1145)
>         at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter$OutputSink.closeLogWriters(HLogSplitter.java:1330)
>         at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter$OutputSink.finishWritingAndClose(HLogSplitter.java:1221)
>         at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLogFileToTemp(HLogSplitter.java:441)
>         at org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLogFileToTemp(HLogSplitter.java:369)
>         at org.apache.hadoop.hbase.regionserver.SplitLogWorker$1.exec(SplitLogWorker.java:113)
>         at org.apache.hadoop.hbase.regionserver.SplitLogWorker.grabTask(SplitLogWorker.java:276)
>         at org.apache.hadoop.hbase.regionserver.SplitLogWorker.taskLoop(SplitLogWorker.java:197)
>         at org.apache.hadoop.hbase.regionserver.SplitLogWorker.run(SplitLogWorker.java:164)
>         at java.lang.Thread.run(Thread.java:662)
> 2012-07-03 12:13:32,575 INFO org.apache.hadoop.hbase.regionserver.SplitLogWorker: SplitLogWorker
****.cloudera.com,57020,1341335300238 exiting

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