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https://issues.apache.org/jira/browse/HBASE-7247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13622595#comment-13622595
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Nicolas Liochon commented on HBASE-7247:
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I'm doing some tests on trunk on recovery.
Test is:
- 1000 empty regions on one RS
- on another computer, all services are running: master, ZK, second RS.
- Stop (cleanly) the first RS.
Recovery (in this case assignment only) takes 2 minutes.
All the time seems to be spent in writing/reading to ZK.
We have ~3000 calls to ZK#transitionNode, including 1000 for tickleOpening.
Each transition is:
sync
readData
setData
Commenting the sync makes no difference (it could be an effect of the test env).
removing tickleOpening brings the result to 80 seconds (vs. 120s)
Checking but not writing in tickleOpening puts us around 85s. I will do a
proper patch with this.
> 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: Nicolas Liochon
> Assignee: Nicolas Liochon
> Fix For: 0.95.1
>
> Attachments: 7247.v1.patch
>
>
> 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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