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https://issues.apache.org/jira/browse/HBASE-3303?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jean-Daniel Cryans updated HBASE-3303:
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Attachment: HBASE-3303-doc.patch
Patch with doc for the book.
> Lower hbase.regionserver.handler.count from 25 back to 10
> ---------------------------------------------------------
>
> Key: HBASE-3303
> URL: https://issues.apache.org/jira/browse/HBASE-3303
> Project: HBase
> Issue Type: Improvement
> Reporter: Jean-Daniel Cryans
> Assignee: Jean-Daniel Cryans
> Fix For: 0.90.0
>
> Attachments: 3303.txt, 3303.txt, HBASE-3303-doc.patch
>
>
> With HBASE-2506 in mind, I tested a low-memory environment (2GB of heap) with
> a lot of concurrent writers using the default write buffer to verify if a
> lower number of handlers actually helps reducing the occurrence full GCs.
> Very unscientifically, at this moment I think it's safe to say that yes, it
> helps.
> With the defaults, I saw a region server struggling more and more because the
> random inserters at some point started filling up all the handlers and were
> all BLOCKED trying to sync the WAL. It's safe to say that each of those
> clients carried a payload that the GC cannot get rid of and it's one that we
> don't account for (as opposed to MemStore and the block cache).
> With a much lower setting of 5, I didn't see the situation.
> It kind of confirms my hypothesis but I need to do more proper testing. In
> the mean time, in order to lower the onslaught of users that write to the ML
> complaining about either GCs or OOMEs, I think we should set the handlers
> back to what it was originally (10) for 0.90.0 and add some documentation
> about configuring hbase.regionserver.handler.count
> I'd like to hear others' thoughts.
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