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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5897) prePut coprocessor hook causing substantial CPU usage
Date Mon, 30 Apr 2012 21:53:50 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5897?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13265414#comment-13265414
] 

Todd Lipcon commented on HBASE-5897:
------------------------------------

bq. So calling doMiniBatchPut multiple times on behalf of the same Put operation should be
happening relatively rarely.

True, unless there's a lot of contention on some rows. In the test I was doing, I was slamming
a fairly small number of rows with puts, so there was a lot of this "back-off" behavior.

I bet we could improve performance by making it continue past a failed lock acquisition and
acquire as many as possible, while pushing those it missed back onto the end of the list.
Right now, as soon as it fails any lock acquisition, it stops the batch there (so we always
do contiguous ranges of ops instead of arbitrary sets)
                
> prePut coprocessor hook causing substantial CPU usage
> -----------------------------------------------------
>
>                 Key: HBASE-5897
>                 URL: https://issues.apache.org/jira/browse/HBASE-5897
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.92.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Critical
>             Fix For: 0.92.2, 0.94.0, 0.96.0
>
>         Attachments: 5897-simple.txt, hbase-5897.txt
>
>
> I was running an insert workload against trunk under oprofile and saw that a significant
portion of CPU usage was going to calling the "prePut" coprocessor hook inside doMiniBatchPut,
even though I don't have any coprocessors installed. I ran a million-row insert and collected
CPU time spent in the RS after commenting out the preput hook, and found CPU usage reduced
by 33%.

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