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https://issues.apache.org/jira/browse/HBASE-6060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13294154#comment-13294154
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ramkrishna.s.vasudevan commented on HBASE-6060:
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bq.Is this a fair characterization?
RegionState is something which the master uses to see the current progress of
the assignment. But regionplan is one thing which will tels me where the
assignment is actually going on.
If master wants to start a new assignment its again the regionplan that gets
changed. So we thought of using that as an indicator. But i agree two systems
AM and SSH take decision based on that..
One more thing on RegionState in RIT is that it is reactive. Based on some
changes in RS it gets updated. But RegionPlan is the one decided by the master.
Every time Assignment starts RegionState in RIT goes thro a set of steps and
may be that is why we are not sure as in what step the RIT is and who made that
change.
We also tried thought of one approach, like can we remove the retry logic
itself in assign? Always use SSH to trigger assignment as in TRUNK the expiry
of server is very much spontaneous now. May be some gaps are there which we
have not yet found.
I should accept one thing is I did not try to change the RegionState in RIT and
was seeing to use the RegionPlan only.
bq.RS update the znode to OPENING form OFFINE before returning from the open
rpc call.
Then this step has to be moved from OpenRegionHandler?
> Regions's in OPENING state from failed regionservers takes a long time to
> recover
> ---------------------------------------------------------------------------------
>
> Key: HBASE-6060
> URL: https://issues.apache.org/jira/browse/HBASE-6060
> Project: HBase
> Issue Type: Bug
> Components: master, regionserver
> Reporter: Enis Soztutar
> Assignee: rajeshbabu
> Fix For: 0.96.0, 0.94.1, 0.92.3
>
> Attachments: 6060-94-v3.patch, 6060-94-v4.patch, 6060-94-v4_1.patch,
> 6060-94-v4_1.patch, 6060-trunk.patch, 6060-trunk.patch, 6060-trunk_2.patch,
> 6060-trunk_3.patch, 6060_alternative_suggestion.txt,
> 6060_suggestion2_based_off_v3.patch, 6060_suggestion_based_off_v3.patch,
> 6060_suggestion_toassign_rs_wentdown_beforerequest.patch,
> HBASE-6060-92.patch, HBASE-6060-94.patch, HBASE-6060-trunk_4.patch,
> HBASE-6060_trunk_5.patch
>
>
> we have seen a pattern in tests, that the regions are stuck in OPENING state
> for a very long time when the region server who is opening the region fails.
> My understanding of the process:
>
> - master calls rs to open the region. If rs is offline, a new plan is
> generated (a new rs is chosen). RegionState is set to PENDING_OPEN (only in
> master memory, zk still shows OFFLINE). See HRegionServer.openRegion(),
> HMaster.assign()
> - RegionServer, starts opening a region, changes the state in znode. But
> that znode is not ephemeral. (see ZkAssign)
> - Rs transitions zk node from OFFLINE to OPENING. See
> OpenRegionHandler.process()
> - rs then opens the region, and changes znode from OPENING to OPENED
> - when rs is killed between OPENING and OPENED states, then zk shows OPENING
> state, and the master just waits for rs to change the region state, but since
> rs is down, that wont happen.
> - There is a AssignmentManager.TimeoutMonitor, which does exactly guard
> against these kind of conditions. It periodically checks (every 10 sec by
> default) the regions in transition to see whether they timedout
> (hbase.master.assignment.timeoutmonitor.timeout). Default timeout is 30 min,
> which explains what you and I are seeing.
> - ServerShutdownHandler in Master does not reassign regions in OPENING
> state, although it handles other states.
> Lowering that threshold from the configuration is one option, but still I
> think we can do better.
> Will investigate more.
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