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https://issues.apache.org/jira/browse/ACCUMULO-1755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15169278#comment-15169278
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ASF GitHub Bot commented on ACCUMULO-1755:
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GitHub user dlmarion opened a pull request:
https://github.com/apache/accumulo/pull/75
ACCUMULO-1755: Modified TSBW so that all client threads will not bloc…
I ditched review board and went back to the drawing board.
Before this change all client threads that were adding mutations to a
BatchWriter would block
when the mutations needed to be written to the tablet servers. This change
gives each client
thread their own MutationWriter object using a ThreadLocal. With this
change only one client
should block on adding the mutations to the sendThreadPool object, and
allows the other client
threads to push mutations onto a new MutationSet.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/accumulo ACCUMULO-1755
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/accumulo/pull/75.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #75
----
commit 9bd48cdbd25a7baf19bbda007a8e36f8ec81cf07
Author: Dave Marion <dlmar...@apache.org>
Date: 2016-02-26T16:26:53Z
ACCUMULO-1755: Modified TSBW so that all client threads will not block on
binMutations
Before this change all client threads that were adding mutations to a
BatchWriter would block
when the mutations needed to be written to the tablet servers. This change
gives each client
thread their own MutationWriter object using a ThreadLocal. With this
change only one client
should block on adding the mutations to the sendThreadPool object, and
allows the other client
threads to push mutations onto a new MutationSet.
----
> 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
> Fix For: 1.8.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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