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https://issues.apache.org/jira/browse/ACCUMULO-1755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15163587#comment-15163587
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Dave Marion commented on ACCUMULO-1755:
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Adam, I have this issue now where i have N clients sharing a batch writer. As
you noted in the description, all the threads wait on binning mutations. I
could use a batch writer per thread, and that may be the solution in the end. I
think I can remove the synchronized modifier from addMutation, but I think in
the end I may just be pushing the problem to an area of the code that the
client has no control over. I'm interested in solving this issue though, any
time you can spare would be appreciated.
> BatchWriter blocks all addMutation calls while binning mutations
> ----------------------------------------------------------------
>
> Key: ACCUMULO-1755
> URL: https://issues.apache.org/jira/browse/ACCUMULO-1755
> Project: Accumulo
> Issue Type: Improvement
> Components: client
> Reporter: Adam Fuchs
> Assignee: Dave Marion
>
> Through code inspection, we found that the BatchWriter bins mutations inside
> of a synchronized block that covers calls to addMutation. Binning potentially
> involves lookups of tablet metadata and processes a fair amount of
> information. We will get better parallelism if we can either unlock the lock
> while binning, dedicate another thread to do the binning, or use one of the
> send threads to do the binning.
> This has not been verified empirically yet, so there is not yet any profiling
> info to indicate the level of improvement that we should expect. Profiling
> and repeatable demonstration of this performance bottleneck should be the
> first step on this ticket.
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