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From "Hiroshi Ikeda (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16023) Fastpath for the FIFO rpcscheduler
Date Mon, 20 Jun 2016 01:55:06 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16023?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15338883#comment-15338883
] 

Hiroshi Ikeda commented on HBASE-16023:
---------------------------------------

Other worrying things:

{code}
    protected CallRunner getCallRunner() throws InterruptedException {
...skip...
        if (this.fastPathHandlerStack != null) {
          this.fastPathHandlerStack.push(this);
          this.semaphore.acquire();
          cr = this.loadedCallRunner;
        } else {
{code}

The loadedCallRunner should be set to null after passing, otherwise that would become sort
of memory leak (in low load).


It is not a bug but
{code}
    private Semaphore semaphore = new Semaphore(1);
...skip...
    FastPathHandler(String name, double handlerFailureThreshhold, BlockingQueue<CallRunner>
q,
...skip...
      this.semaphore.drainPermits();
{code}

It is better to just create an instance of Semaphore with no permit.

> Fastpath for the FIFO rpcscheduler
> ----------------------------------
>
>                 Key: HBASE-16023
>                 URL: https://issues.apache.org/jira/browse/HBASE-16023
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Performance, rpc
>    Affects Versions: 2.0.0, 1.3.0
>            Reporter: stack
>            Assignee: stack
>             Fix For: 2.0.0, 1.3.0
>
>         Attachments: HBASE-16023.addenum.patch, HBASE-16023.branch-1.001.patch, hits.nofifo.fifoplusfp.fifownofp.hacks.png
>
>
> This is an idea copied from kudu where we skip queuing a request if there is a handler
ready to go; we just do a direct handoff from reader to handler.
> Makes for close to a %20 improvement in random read workloadc testing moving the bottleneck
to HBASE-15716 and to returning the results.



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