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From "Prakash Khemani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4007) distributed log splitting can get indefinitely stuck
Date Mon, 20 Jun 2011 17:02:48 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4007?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13052067#comment-13052067

Prakash Khemani commented on HBASE-4007:

@mingjian What you are talking about is probably a different issue. The scenario you have
described can happen when 1. Master puts up a task. 2. No one acquires the task. 3. Master
puts up a RESCAN node asking everyone to re-look at the zk splitlog task list.

The bug described in this jira will happen in the following way (I have not encountered it
yet but should be easy to reproduce)

a/ A splitlog task is slow. Master has already moved the task from one worker to another 3
times. It is with the 4th worker now. Even if the 4th worker takes too long doing this task
the master is not going to do anything about it.

b/ the 4th worker dies.

c/ the task will hang. 

Master has to resubmit the task when the 4th worker dies. 

> distributed log splitting can get indefinitely stuck
> ----------------------------------------------------
>                 Key: HBASE-4007
>                 URL: https://issues.apache.org/jira/browse/HBASE-4007
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Prakash Khemani
>            Assignee: Prakash Khemani
> After the configured number of retries SplitLogManager is not going to resubmit log-split
tasks. In this situation even if the splitLogWorker that owns the task dies the task will
not get resubmitted.
> When a regionserver goes away then all the split-log tasks that it owned should be resubmitted
by the SplitLogMaster.

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