Mailing-List: contact issues-help@hbase.apache.org; run by ezmlm
Precedence: bulk
Date: Wed, 4 Jan 2012 10:17:39 +0000 (UTC)
From: "Zhihong Yu (Commented) (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: 
 <399250066.4111.1325672259525.JavaMail.tomcat@hel.zones.apache.org>
In-Reply-To: 
 <1918412762.34095.1324439491031.JavaMail.tomcat@hel.zones.apache.org>
Subject: [jira] [Commented] (HBASE-5081) Distributed log splitting
 deleteNode races against splitLog retry
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HBASE-5081?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13179394#comment-13179394 ] 

Zhihong Yu commented on HBASE-5081:
-----------------------------------

In the above scenario, would there be many "duplicate log" messages in master log file ?
                
> Distributed log splitting deleteNode races against splitLog retry 
> ------------------------------------------------------------------
>
>                 Key: HBASE-5081
>                 URL: https://issues.apache.org/jira/browse/HBASE-5081
>             Project: HBase
>          Issue Type: Bug
>          Components: wal
>    Affects Versions: 0.92.0, 0.94.0
>            Reporter: Jimmy Xiang
>            Assignee: Prakash Khemani
>             Fix For: 0.92.0
>
>         Attachments: 0001-HBASE-5081-jira-Distributed-log-splitting-deleteNode.patch, 0001-HBASE-5081-jira-Distributed-log-splitting-deleteNode.patch, 0001-HBASE-5081-jira-Distributed-log-splitting-deleteNode.patch, 0001-HBASE-5081-jira-Distributed-log-splitting-deleteNode.patch, distributed-log-splitting-screenshot.png, hbase-5081-patch-v6.txt, hbase-5081-patch-v7.txt, hbase-5081_patch_for_92_v4.txt, hbase-5081_patch_v5.txt, patch_for_92.txt, patch_for_92_v2.txt, patch_for_92_v3.txt
>
>
> Recently, during 0.92 rc testing, we found distributed log splitting hangs there forever.  Please see attached screen shot.
> I looked into it and here is what happened I think:
> 1. One rs died, the servershutdownhandler found it out and started the distributed log splitting;
> 2. All three tasks failed, so the three tasks were deleted, asynchronously;
> 3. Servershutdownhandler retried the log splitting;
> 4. During the retrial, it created these three tasks again, and put them in a hashmap (tasks);
> 5. The asynchronously deletion in step 2 finally happened for one task, in the callback, it removed one
> task in the hashmap;
> 6. One of the newly submitted tasks' zookeeper watcher found out that task is unassigned, and it is not
> in the hashmap, so it created a new orphan task.
> 7.  All three tasks failed, but that task created in step 6 is an orphan so the batch.err counter was one short,
> so the log splitting hangs there and keeps waiting for the last task to finish which is never going to happen.
> So I think the problem is step 2.  The fix is to make deletion sync, instead of async, so that the retry will have
> a clean start.
> Async deleteNode will mess up with split log retrial.  In extreme situation, if async deleteNode doesn't happen
> soon enough, some node created during the retrial could be deleted.
> deleteNode should be sync.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira