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From "Hiroshi Ikeda (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14331) a single callQueue related improvements
Date Mon, 14 Sep 2015 10:07:46 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14743314#comment-14743314
] 

Hiroshi Ikeda commented on HBASE-14331:
---------------------------------------

{quote}
Personally I would prefer a series of smaller patches. I.e. can't we just optionally replace
the LinkedBlockingQueues used with with the SemaphoreBased* based ones, and then add the nice
factories in a 2nd patch? 
{quote}

{{BlockingQueue}} has too many methods and its contracts. I found I just created broken implementations.
Fortunately, a few methods were required in the logic, and I extracted them into a small interface
{{CallQueue}}.

{quote}
Do you think that with this patch we can get rid of the multi call queue logic? I.e. go back
have a single queue (or one for reader and one for writers).
{quote}

I think there is no reason to use multi queues. One should use a single queue until there
is truly no choice to use multi queues.

> a single callQueue related improvements
> ---------------------------------------
>
>                 Key: HBASE-14331
>                 URL: https://issues.apache.org/jira/browse/HBASE-14331
>             Project: HBase
>          Issue Type: Improvement
>          Components: IPC/RPC, Performance
>            Reporter: Hiroshi Ikeda
>            Assignee: Hiroshi Ikeda
>            Priority: Minor
>         Attachments: BlockingQueuesPerformanceTestApp-output.pdf, BlockingQueuesPerformanceTestApp-output.txt,
BlockingQueuesPerformanceTestApp.java, CallQueuePerformanceTestApp.java, HBASE-14331-V2.patch,
HBASE-14331-V3.patch, HBASE-14331.patch, HBASE-14331.patch, SemaphoreBasedBlockingQueue.java,
SemaphoreBasedLinkedBlockingQueue.java, SemaphoreBasedPriorityBlockingQueue.java
>
>
> {{LinkedBlockingQueue}} well separates locks between the {{take}} method and the {{put}}
method, but not between takers, and not between putters. These methods are implemented to
take locks at the almost beginning of their logic. HBASE-11355 introduces multiple call-queues
to reduce such possible congestion, but I doubt that it is required to stick to {{BlockingQueue}}.
> There are the other shortcomings of using {{BlockingQueue}}. When using multiple queues,
since {{BlockingQueue}} blocks threads it is required to prepare enough threads for each queue.
It is possible that there is a queue starving for threads while there is another queue where
threads are idle. Even if you can tune parameters to avoid such situations, the tuning is
not so trivial.
> I suggest using a single {{ConcurrentLinkedQueue}} with {{Semaphore}}.



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