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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-4718) More-efficient ExecutorService for improved throughput
Date Fri, 16 May 2014 22:06:21 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-4718?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Benedict updated CASSANDRA-4718:
--------------------------------

    Attachment: austin_diskbound_read.svg

For reference, a plot of reads from a much larger than memory dataset against the austin cluster.
There's a lot of variability, but no appreciable difference between the two, which is what
I would expect (but good to confirm)

> More-efficient ExecutorService for improved throughput
> ------------------------------------------------------
>
>                 Key: CASSANDRA-4718
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4718
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>            Assignee: Benedict
>            Priority: Minor
>              Labels: performance
>             Fix For: 2.1.0
>
>         Attachments: 4718-v1.patch, PerThreadQueue.java, austin_diskbound_read.svg, aws.svg,
aws_read.svg, backpressure-stress.out.txt, baq vs trunk.png, belliotsmith_branches-stress.out.txt,
jason_read.svg, jason_read_latency.svg, jason_write.svg, op costs of various queues.ods, stress
op rate with various queues.ods, stress_2014May15.txt, stress_2014May16.txt, v1-stress.out
>
>
> Currently all our execution stages dequeue tasks one at a time.  This can result in contention
between producers and consumers (although we do our best to minimize this by using LinkedBlockingQueue).
> One approach to mitigating this would be to make consumer threads do more work in "bulk"
instead of just one task per dequeue.  (Producer threads tend to be single-task oriented by
nature, so I don't see an equivalent opportunity there.)
> BlockingQueue has a drainTo(collection, int) method that would be perfect for this. 
However, no ExecutorService in the jdk supports using drainTo, nor could I google one.
> What I would like to do here is create just such a beast and wire it into (at least)
the write and read stages.  (Other possible candidates for such an optimization, such as the
CommitLog and OutboundTCPConnection, are not ExecutorService-based and will need to be one-offs.)
> AbstractExecutorService may be useful.  The implementations of ICommitLogExecutorService
may also be useful. (Despite the name these are not actual ExecutorServices, although they
share the most important properties of one.)



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