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From "Hiroshi Ikeda (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-14331) a single callQueue related improvements
Date Mon, 31 Aug 2015 07:20:46 GMT

     [ https://issues.apache.org/jira/browse/HBASE-14331?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Hiroshi Ikeda updated HBASE-14331:
    Attachment: BlockingQueuesPerformanceTestApp-output.pdf

Added a result of the performance test in my environment, which has 8 cpu cores.

It compares (1){{LinkedBlockingQueue}} in the standard Java library, (2){{BoundedPriorityBlockingQueue}}
in HBase, and the newly implemented classes, (3){{SemaphoreBasedLinkedBlockingQueue}} and
(4){{SemaphoreBasedPriorityBlockingQueue}}. I just changed the code of the test application
to add (2){{BoundedPriorityBlockingQueue}}.

The tasks are just executing {{Thread.yield}} and there should be excessively context switches,
but the result says, the reading threads in the existing queues, (1){{LinkedBlockingQueue}}
and (2){{BoundPriorityBlockingQueue}}, are rarely waken up. That means many reading threads
are blocked in the 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
>            Priority: Minor
>         Attachments: BlockingQueuesPerformanceTestApp-output.pdf, BlockingQueuesPerformanceTestApp-output.txt,
BlockingQueuesPerformanceTestApp.java, CallQueuePerformanceTestApp.java, 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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