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https://issues.apache.org/jira/browse/HBASE-6060?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13289576#comment-13289576
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ramkrishna.s.vasudevan commented on HBASE-6060:
-----------------------------------------------
{code}
final String encodedName = state.getRegion().getEncodedName();
final List<ServerName> destServers =
serverManager.createDestinationServersList(serverToExclude);
if (destServers.isEmpty()){
LOG.warn("Can't move the region " + encodedName +
", there is no destination server available.");
return null;
}
{code}
Thought we can extract this out before calling getRegionPlan so that if we get
a null we know there are no servers to assign.
After this we should use the destServers and pass it to getRegionPlan. Now if
getRegionPlan gives a null then we are sure that dont assign the regions yet.
But now if someone needs to use getRegionPlan they need to make a call to the
code above know the result and then use getRegionPlan passing the destServers
(which again can be null).
If you see the patch attached earlier we tried to use a boolean var in
regionplan to know if we can use the plan or not.
Can we try to make the destination as null if we want to say dont assign the
region yet?
> 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: Enis Soztutar
> 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, HBASE-6060-92.patch, HBASE-6060-94.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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