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https://issues.apache.org/jira/browse/HBASE-7247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13507607#comment-13507607
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Jimmy Xiang commented on HBASE-7247:
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If one region server is opening a lot of regions, we just need one handler to
tickle the opening. Master just needs to know the region server is still
running so that it doesn't time out the assignment.
To me, this is an overkill. We can combine this logic and something else, for
example, to detect if a regionserver is dead.
We used to have the 'owernership' issue as Stack mentioned. Now, I think we
are fine since AM should have a consistent view of region states.
> Assignment performances decreased by 50% because of
> regionserver.OpenRegionHandler#tickleOpening
> ------------------------------------------------------------------------------------------------
>
> Key: HBASE-7247
> URL: https://issues.apache.org/jira/browse/HBASE-7247
> Project: HBase
> Issue Type: Improvement
> Components: master, Region Assignment, regionserver
> Affects Versions: 0.96.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Critical
>
> The regionserver.OpenRegionHandler#tickleOpening updates the region znode as
> "Do this so master doesn't timeout this region-in-transition.".
> However, on the usual test, this makes the assignment time of 1500 regions
> goes from 70s to 100s, that is, we're 50% slower because of this.
> More generally, ZooKeper commits to disk all the data update, and this takes
> time. Using it to provide a keep alive seems overkill. At the very list, it
> could be made asynchronous.
> I'm not sure how necessary these updates are required (I need to go deeper in
> the internal, feedback welcome), but it seems very important to optimize
> this... The trival fix would be to make this optional.
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