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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-1755) BatchWriter blocks all addMutation calls while binning mutations
Date Wed, 24 Feb 2016 18:13:18 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-1755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15163447#comment-15163447
] 

Josh Elser commented on ACCUMULO-1755:
--------------------------------------

At a glance, wouldn't a simple queue that we could dump mutations on be a simple change (would
just require some memory mgmt controls)? Clients can push onto the queue to buffer mutations
as long as there is free memory. Heck, we could even let users pass in the queue (and totally
ignore the memory control problem). The BW can then consume and bin mutations in batches from
the queue. It seems like that might be more simple to me, but I might be missing some details
too :)

> 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
>
> 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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