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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15047) Try spin lock for MVCC completion
Date Tue, 29 Dec 2015 23:34:49 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15074434#comment-15074434
] 

stack commented on HBASE-15047:
-------------------------------

Radical. At first blush, we will be waiting too long in mvcc to spin and who says the currently
scheduled thread is next in line for mvcc and what is to prevent all CPUs being here spinning
with no thread free to make forward progess? I'll try it though.

> Try spin lock for MVCC completion
> ---------------------------------
>
>                 Key: HBASE-15047
>                 URL: https://issues.apache.org/jira/browse/HBASE-15047
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Elliott Clark
>            Assignee: Elliott Clark
>         Attachments: HBASE-15047.patch
>
>
> Waits/Notify is very very expensive since it can cost a thread scheduling. There should
only ever be a few threads ( < Num Cores ) running. So it should be possible to spin and
use compare and swap to update the read point.



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