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https://issues.apache.org/jira/browse/CASSANDRA-4718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13986626#comment-13986626
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Benedict commented on CASSANDRA-4718:
-------------------------------------
For comparison, a graph of Jason's results:
https://docs.google.com/spreadsheets/d/1mLxyY9syaAlDb1ALGQ-oF7Qo0tQffbcNgFMVPktde88/edit?usp=sharing
I'd like to do a couple of things here:
# Tweak the Low Signal patch to potentially signal more intelligently rather
than just always aggregating the last 5us of requests
# Try increasing the queue length
# Try these tests for a standardized load - the stress functionality we're
using is great for giving a good ballpark idea of performance, but it varies
the number of ops with each run, so running with a fixed 10M ops per run might
be useful (stress could maybe do with an "ops per thread" option, as for the
low thread counts this is a lot of work, but for high counts not very much)
The lowsignal patch looks to outperform at certain thresholds, but underperform
at others, and I'm hoping 1 and 2 might help us make it better overall. At high
thread counts the difference is almost 20% for writes, which is non-trivial.
> 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: Jason Brown
> Priority: Minor
> Labels: performance
> Fix For: 2.1.0
>
> Attachments: 4718-v1.patch, PerThreadQueue.java,
> backpressure-stress.out.txt, baq vs trunk.png, op costs of various
> queues.ods, stress op rate with various queues.ods, 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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