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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6423) Writes should not block reads on blocking updates to memstores
Date Fri, 30 Nov 2012 06:33:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13507138#comment-13507138
] 

stack commented on HBASE-6423:
------------------------------

[~jxiang] You doing the createConf stuff in the test that Lars above refers too because there
is no setup in this old junit3 TestHRegion and you need to get your custom config. in there
each time test runs?

If so, +1 on commit.  Otherwise, what Lars asks.
                
> Writes should not block reads on blocking updates to memstores
> --------------------------------------------------------------
>
>                 Key: HBASE-6423
>                 URL: https://issues.apache.org/jira/browse/HBASE-6423
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Karthik Ranganathan
>            Assignee: Jimmy Xiang
>         Attachments: trunk-6423.patch, trunk-6423_v2.1.patch, trunk-6423_v2.patch, trunk-6423_v3.2.patch
>
>
> We have a big data use case where we turn off WAL and have a ton of reads and writes.
We found that:
> 1. flushing a memstore takes a while (GZIP compression)
> 2. incoming writes cause the new memstore to grow in an unbounded fashion
> 3. this triggers blocking memstore updates
> 4. in turn, this causes all the RPC handler threads to block on writes to that memstore
> 5. we are not able to read during this time as RPC handlers are blocked
> At a higher level, we should not hold up the RPC threads while blocking updates, and
we should build in some sort of rate control.

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