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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5849) On first cluster startup, RS aborts if root znode is not available
Date Tue, 24 Apr 2012 04:31:10 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13260208#comment-13260208
] 

stack commented on HBASE-5849:
------------------------------

I tried it before committing and it passed then.  I just tried it on trunk now:

{code}
-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.apache.hadoop.hbase.TestClusterBootOrder
2012-04-23 21:27:45.213 java[97823:d007] Unable to load realm info from SCDynamicStore
Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 19.727 sec

Results :

Tests run: 2, Failures: 0, Errors: 0, Skipped: 0

[INFO] 
[INFO] --- maven-surefire-plugin:2.10:test (secondPartTestsExecution) @ hbase ---
[INFO] Tests are skipped.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 34.313s
[INFO] Finished at: Mon Apr 23 21:28:02 PDT 2012
[INFO] Final Memory: 21M/81M
[INFO] ------------------------------------------------------------------------
{code}
                
> On first cluster startup, RS aborts if root znode is not available
> ------------------------------------------------------------------
>
>                 Key: HBASE-5849
>                 URL: https://issues.apache.org/jira/browse/HBASE-5849
>             Project: HBase
>          Issue Type: Bug
>          Components: master, regionserver, zookeeper
>    Affects Versions: 0.92.2, 0.96.0, 0.94.1
>            Reporter: Enis Soztutar
>            Assignee: Enis Soztutar
>             Fix For: 0.92.2, 0.94.0
>
>         Attachments: 5849v3.txt, HBASE-5849_v1.patch, HBASE-5849_v2.patch
>
>
> When launching a fresh new cluster, the master has to be started first, which might create
race conditions for starting master and rs at the same time. 
> Master startup code is smt like this: 
>  - establish zk connection
>  - create root znodes in zk (/hbase)
>  - create ephemeral node for master /hbase/master, 
>  Region server start up code is smt like this: 
>  - establish zk connection
>  - check whether the root znode (/hbase) is there. If not, shutdown. 
>  - wait for the master to create znodes /hbase/master
> So, the problem is on the very first launch of the cluster, RS aborts to start since
/hbase znode might not have been created yet (only the master creates it if needed). Since
/hbase/ is not deleted on cluster shutdown, on subsequent cluster starts, it does not matter
which order the servers are started. So this affects only first launchs. 

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