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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-1755) BatchWriter blocks all addMutation calls while binning mutations
Date Mon, 29 Feb 2016 15:29:18 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-1755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15171985#comment-15171985
] 

ASF GitHub Bot commented on ACCUMULO-1755:
------------------------------------------

Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/75#discussion_r54424394
  
    --- Diff: core/src/main/java/org/apache/accumulo/core/client/impl/TabletServerBatchWriter.java
---
    @@ -629,6 +639,8 @@ public void run() {
     
         private static final int MUTATION_BATCH_SIZE = 1 << 17;
         private final ExecutorService sendThreadPool;
    +    private final LinkedTransferQueue<Runnable> queue = new LinkedTransferQueue<>();
    +    private final ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 10L, TimeUnit.SECONDS,
queue);
    --- End diff --
    
    Would be nice to name thread.  Also it should be a daemon thread (I think it will not
be by default).  These are things I think that SimpleThreadPool does (may have name wrong,
you were using it earlier).


> 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: 50m
>  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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