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https://issues.apache.org/jira/browse/HBASE-722?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12611459#action_12611459
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Billy Pearson commented on HBASE-722:
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Sense we compact in the background if needed after loading the region on
startup and the compaction thread does not effect the loading of newly
assigned region opens from the master. I thank shutdown should close all
regions unless compacting and close the last one after the compaction is done.
That will not always be a fast shutdown but it will be faster then if there is
compaction on more then one region while shutting down.
> Shutdown and Compactions
> ------------------------
>
> Key: HBASE-722
> URL: https://issues.apache.org/jira/browse/HBASE-722
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Billy Pearson
> Priority: Trivial
> Fix For: 0.3.0
>
>
> Currently I thank the region server closes the region spits in a set order
> this same order is used in the compaction/spit thread after a startup and all
> regions need compaction.
> This causes the shutdown time to take a vary long time depending on what
> region the server is compacting.
> I have seen my cluster take more then 60 mins to shutdown waiting for
> several regions to finish compaction.
> The problem I am seeing is say the compaction thread is working on a on
> region 2 of 4 in the list.
> When the region server get the MSG_REGIONSERVER_QUIESCE from the master it
> closes in order from 1-4
> So it closes region 1 and waits for region 2 to finish compaction before
> closing it.
> The problem is it never closes region split 3 or 4 while waiting for region 2
> to complete the compaction.
> So example say 3 and 4 regions are waiting to be compacted also. When region
> 2 is done region 3 start compaction within milliseconds of 2's finished
> compaction.
> This happens faster then the region server can close region 3 so the region
> server hangs around compacting regions until it run out of open regions
> needing compact.
> With a lot of regions this could hang some region server a long time to
> Shutdown the cluster.
> Solutions 1 or 2 below will work I thank
> 1. Close all regions not currently getting compaction so when the compaction
> thread complete it has no other regions open to compact
> 2. Empty the compaction que so it has no other regions to compact when done
> with the current one.
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