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From "Ashu Pachauri (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14802) Replaying server crash recovery procedure after a failover causes incorrect handling of deadservers
Date Sun, 15 Nov 2015 19:02:10 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15005992#comment-15005992
] 

Ashu Pachauri commented on HBASE-14802:
---------------------------------------

I don't see why starting the mini cluster should time out only for this test if it has something
to do with the change itself. The only thing I can think of is that the test puts a timeout
of 15 seconds and the mini cluster fails to come up in 15 seconds. I will move the mini cluster
startup to the setup stage, rather than inside the test itself.

> Replaying server crash recovery procedure after a failover causes incorrect handling
of deadservers
> ---------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-14802
>                 URL: https://issues.apache.org/jira/browse/HBASE-14802
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>    Affects Versions: 2.0.0, 1.2.0, 1.2.1
>            Reporter: Ashu Pachauri
>            Assignee: Ashu Pachauri
>             Fix For: 2.0.0, 1.2.0, 1.3.0
>
>         Attachments: HBASE-14802-1.patch, HBASE-14802-2.patch, HBASE-14802-3.patch, HBASE-14802.patch
>
>
> The way dead servers are processed is that a ServerCrashProcedure is launched for a server
after it is added to the dead servers list. 
> Every time a server is added to the dead list, a counter "numProcessing" is incremented
and it is decremented when a crash recovery procedure finishes. Since, adding a dead server
and recovering it are two separate events, it can cause inconsistencies.
> If a master failover occurs in the middle of the crash recovery, the numProcessing counter
resets but the ServerCrashProcedure is replayed by the new master. This causes the counter
to go negative and makes the master think that dead servers are still in process of recovery.

> This has ramifications on the balancer that the balancer ceases to run after such a failover.



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