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From "Jerry He (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8519) Backup master will never come up if primary master dies during initialization
Date Sat, 11 May 2013 06:47:17 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13655179#comment-13655179

Jerry He commented on HBASE-8519:

The missing part seems to be this.
The backup master only check the clusterStateZNode once at the end when it wakes up and tries
to be master again.
It is not notified if the clusterStateZNode has ever been up or not before that.

The real 'stop' case is: clusterStateZNode up --> clusterStateZNode down

The backup master needs to watch for clusterStateZNode. If it is not aware clusterStateZNode
has ever been up 
or was up in its whole life, it should treat it as not a real 'stop' case at the end.

The if condition would become:

  if (clusterHasBeenUp && !clusterStatusTracker.isClusterUp()) {
            "Cluster went down before this master became active");

Comments, please.
> Backup master will never come up if primary master dies during initialization
> -----------------------------------------------------------------------------
>                 Key: HBASE-8519
>                 URL: https://issues.apache.org/jira/browse/HBASE-8519
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>    Affects Versions: 0.94.7, 0.95.0
>            Reporter: Jerry He
>            Assignee: Jerry He
>            Priority: Minor
>             Fix For: 0.98.0
> The problem happens if primary master dies after becoming master but before it completes
initialization and calls clusterStatusTracker.setClusterUp(),
> The backup master will try to become the master, but will shutdown itself promptly because
it sees 'the cluster is not up'.
> This is the backup master log:
> 2013-05-09 15:08:05,568 INFO org.apache.hadoop.hbase.master.metrics.MasterMetrics: Initialized
> 2013-05-09 15:08:05,573 DEBUG org.apache.hadoop.hbase.master.HMaster: HMaster started
in backup mode.  Stalling until master znode is written.
> 2013-05-09 15:08:05,589 INFO org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper:
Node /hbase/master already exists and this is not a retry
> 2013-05-09 15:08:05,590 INFO org.apache.hadoop.hbase.master.ActiveMasterManager: Adding
ZNode for /hbase/backup-masters/xxx.com,60000,1368137285373 in backup master directory
> 2013-05-09 15:08:05,595 INFO org.apache.hadoop.hbase.master.ActiveMasterManager: Another
master is the active master, xxx.com,60000,1368137283107; waiting to become the next active
> 2013-05-09 15:09:45,006 DEBUG org.apache.hadoop.hbase.master.ActiveMasterManager: No
master available. Notifying waiting threads
> 2013-05-09 15:09:45,006 INFO org.apache.hadoop.hbase.master.HMaster: Cluster went down
before this master became active
> 2013-05-09 15:09:45,006 DEBUG org.apache.hadoop.hbase.master.HMaster: Stopping service
> 2013-05-09 15:09:45,006 INFO org.apache.hadoop.ipc.HBaseServer: Stopping server on 60000
> In ActiveMasterManager::blockUntilBecomingActiveMaster()
> {code}
>   ..
>   if (!clusterStatusTracker.isClusterUp()) {
>           this.master.stop(
>             "Cluster went down before this master became active");
>         }
>   ..
> {code}

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