[jira] Commented: (HBASE-1740) ICV has a subtle race condition only visible under high load

["stack (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12754357#action_12754357 ] 

stack commented on HBASE-1740:
------------------------------

Reviewed and ran unit tests.  All pass but the broken ITHBase test.  Committed branch and trunk.

> ICV has a subtle race condition only visible under high load
> ------------------------------------------------------------
>
>                 Key: HBASE-1740
>                 URL: https://issues.apache.org/jira/browse/HBASE-1740
>             Project: Hadoop HBase
>          Issue Type: Bug
>    Affects Versions: 0.20.0
>            Reporter: ryan rawson
>            Assignee: ryan rawson
>             Fix For: 0.20.1
>
>         Attachments: HBASE-1740-test.patch, HBASE-1740.patch, HBASE-icv.patch
>
>
> ICV demonstrates a race condition under high load.  The result is a duplicate KeyValue with the same timestamp, at first in the memcache, and in hfile, then both in hfile.  The get/scan code doesnt know which one to read, and picks one arbitrarily.  One of the keyvalues is correct, one is incorrect.
> What happens at a deeper level:
> - we start an ICV
> - a snapshot happens and moves the memstore to the snapshot
> - the ICV code puts a key-value into memstore that has the same timestamp as a keyvalue in the snapshot.
> This is a deep race condition and several attempts to fix it failed in production here at SU.  This issue is about a more permanent fix.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.