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Date: Thu, 29 Dec 2011 18:39:32 +0000 (UTC)
From: "jiraposter@reviews.apache.org (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-5099) ZK event thread waiting for root
 region while server shutdown handler waiting for event thread to finish
 distributed log splitting to recover the region sever the root region is on
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    [ https://issues.apache.org/jira/browse/HBASE-5099?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13177311#comment-13177311 ] 

jiraposter@reviews.apache.org commented on HBASE-5099:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/3323/
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(Updated 2011-12-29 18:38:54.473524)


Review request for hbase, Ted Yu and Michael Stack.


Changes
-------

Updated per Ted's comment.  Also separated the test class and added a possible testcase.


Summary
-------

Per discussion with Ted (on issues), I put up a patch to run tryRecoveringExpiredZKSession() in a separate thread and time it out and fail the recovery if it is stuck somewhere.

I added a test to test the abort method.  However, for the mini cluster, becomeActiveMaster() doesn't succeed so the abort method ends up always aborted.  So the actually success recovery is not tested.


This addresses bug HBASE-5099.
    https://issues.apache.org/jira/browse/HBASE-5099


Diffs (updated)
-----

  src/main/java/org/apache/hadoop/hbase/master/HMaster.java a5935a6 
  src/test/java/org/apache/hadoop/hbase/master/TestMasterRecovery.java PRE-CREATION 

Diff: https://reviews.apache.org/r/3323/diff


Testing
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mvn -PlocalTests -Dtest=TestMaster* clean test


Thanks,

Jimmy


> ZK event thread waiting for root region while server shutdown handler waiting for event thread to finish distributed log splitting to recover the region sever the root region is on
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-5099
>                 URL: https://issues.apache.org/jira/browse/HBASE-5099
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.92.0, 0.94.0
>            Reporter: Jimmy Xiang
>            Assignee: Jimmy Xiang
>         Attachments: ZK-event-thread-waiting-for-root.png, distributed-log-splitting-hangs.png, hbase-5099-v2.patch, hbase-5099.patch
>
>
> A RS died.  The ServerShutdownHandler kicked in and started the logspliting.  SpliLogManager
> installed the tasks asynchronously, then started to wait for them to complete.
> The task znodes were not created actually.  The requests were just queued.
> At this time, the zookeeper connection expired.  HMaster tried to recover the expired ZK session.
> During the recovery, a new zookeeper connection was created.  However, this master became the
> new master again.  It tried to assign root and meta.
> Because the dead RS got the old root region, the master needs to wait for the log splitting to complete.
> This waiting holds the zookeeper event thread.  So the async create split task is never retried since
> there is only one event thread, which is waiting for the root region assigned.

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