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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4718) More-efficient ExecutorService for improved throughput
Date Mon, 19 May 2014 12:06:40 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14001621#comment-14001621
] 

Jonathan Ellis commented on CASSANDRA-4718:
-------------------------------------------

bq. I can patch stress briefly to force it to run all thread counts in the requested range,
instead of stopping when it hits a plateau

That sounds like a good option to have.

bq. when we did May 15 (which is completely different test btw, addressing your point from
previous comment) there was almost no disk activity after original page cache warm up

That doesn't sound right to me, all the number from May 15 are 7k-14k ops/s which is disk
bound territory.

> 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_run1.svg, jason_run2.svg, jason_run3.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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