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https://issues.apache.org/jira/browse/HBASE-4842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13154788#comment-13154788
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Jonathan Hsieh commented on HBASE-4842:
---------------------------------------
The story behind this problem.
HBCK repairs a bad assignment using the admin interface to reassign a
particular region. offlining the region in ZK. This calls master.assign --
eventually the master uses its serverManager and issues an
HRegionServer.openRegion().
Looks like the HRegionServer.openRegion being essentially asynchronous and
causes the failure. The call submits an OpenRegionHandler (ORH) callback to
the RS's ExecutorService and then immediately returns the RegionState to OPENED.
The ORH thread calls ORH.process -> updateMeta, which creates a
PostOpenDeployTaskThread and starts another thread that calls
HRegionServer.postOpenDeployTasks -> MetaEditor.updateRegionLocation which
updates the meta table.
The problem is that the RegionState OPENED is reported to the master even
though it may not have written all its new assignment to META yet.
> [hbck] Fix intermittent failures on TestHBaseFsck.testHBaseFsck
> ---------------------------------------------------------------
>
> Key: HBASE-4842
> URL: https://issues.apache.org/jira/browse/HBASE-4842
> Project: HBase
> Issue Type: Bug
> Reporter: Jonathan Hsieh
>
> Its seems that on the 0.92 branch in particular, TestHBaseFsck.testHBaseFsck
> is intermittently failing.
> In the test, a region's assignment is purposely changed in META but not in
> ZK. After the equivalent of 'hbck -fix', a subsequent check that should be
> clean comes up with a new ZK assignment but with META still being
> inconsistent with ZK. The RS in ZK sometimes this points to the same RS, but
> sometimes it "moves" to another ZK.
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