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From "Hiroshi Ikeda (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15146) Don't block on Reader threads queueing to a scheduler queue
Date Wed, 22 Jun 2016 08:51:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15146?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15343934#comment-15343934
] 

Hiroshi Ikeda commented on HBASE-15146:
---------------------------------------

That seems based on the fact that there are some clients which don't wait the response of
the previously sent request. Even though a server sends the busy signal to clients, that is
less effective unless such badly behaved clients stop sending their requests.

{quote}
bq.Selector.select immediately causes a context switch when an event occurs, 

Yes it does, and you want to get the reader threads back to the calling select as fast as
possible. 
{quote}

I meant Select.select has the possibility to greatly reduce throughput by overhead of context
switches.


> Don't block on Reader threads queueing to a scheduler queue
> -----------------------------------------------------------
>
>                 Key: HBASE-15146
>                 URL: https://issues.apache.org/jira/browse/HBASE-15146
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 1.2.0
>            Reporter: Elliott Clark
>            Assignee: Elliott Clark
>            Priority: Blocker
>             Fix For: 2.0.0, 1.2.0, 1.3.0
>
>         Attachments: HBASE-15146-v7.patch, HBASE-15146-v8.patch, HBASE-15146-v8.patch,
HBASE-15146.0.patch, HBASE-15146.1.patch, HBASE-15146.2.patch, HBASE-15146.3.patch, HBASE-15146.4.patch,
HBASE-15146.5.patch, HBASE-15146.6.patch
>
>
> Blocking on the epoll thread is awful. The new rpc scheduler can have lots of different
queues. Those queues have different capacity limits. Currently the dispatch method can block
trying to add the the blocking queue in any of the schedulers.
> This causes readers to block, tcp acks are delayed, and everything slows down.



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