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https://issues.apache.org/jira/browse/CASSANDRA-4718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13985658#comment-13985658
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Benedict commented on CASSANDRA-4718:
-------------------------------------
I've uploaded a slight variant of the patch
[here|https://github.com/belliottsmith/cassandra/tree/4718-lowsignal] - this
introduces a special FJP for that processing native transport work, that avoids
blocking on enqueue to the pool unless the configured limit has been reached.
Instead we schedule a ForkJoinTask that sleeps for 5us, forking any work that
has been queued in the interval (and going to sleep only if no work has been
seen in the past 5ms). This permits the connection worker threads to return to
servicing their connections more promptly.
It has only a modest effect on my box, but it does give a 5-10% bump in native
transport performance.
> 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, 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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