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https://issues.apache.org/jira/browse/HBASE-6122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13284961#comment-13284961
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Lars Hofhansl commented on HBASE-6122:
--------------------------------------
+1 patch looks good to me.
> Backup master does not become Active master after ZK exception
> --------------------------------------------------------------
>
> Key: HBASE-6122
> URL: https://issues.apache.org/jira/browse/HBASE-6122
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.0
> Reporter: ramkrishna.s.vasudevan
> Fix For: 0.92.2, 0.96.0, 0.94.1
>
> Attachments: HBASE-6122_0.92.patch, HBASE-6122_0.94.patch
>
>
> -> Active master gets ZK expiry exception.
> -> Backup master becomes active.
> -> The previous active master retries and becomes the back up master.
> Now when the new active master goes down and the current back up master comes
> up, it goes down again with the zk expiry exception it got in the first step.
> {code}
> if (abortNow(msg, t)) {
> if (t != null) LOG.fatal(msg, t);
> else LOG.fatal(msg);
> this.abort = true;
> stop("Aborting");
> }
> {code}
> In ActiveMasterManager.blockUntilBecomingActiveMaster we try to wait till the
> back up master becomes active.
> {code}
> synchronized (this.clusterHasActiveMaster) {
> while (this.clusterHasActiveMaster.get() && !this.master.isStopped()) {
> try {
> this.clusterHasActiveMaster.wait();
> } catch (InterruptedException e) {
> // We expect to be interrupted when a master dies, will fall out if
> so
> LOG.debug("Interrupted waiting for master to die", e);
> }
> }
> if (!clusterStatusTracker.isClusterUp()) {
> this.master.stop("Cluster went down before this master became
> active");
> }
> if (this.master.isStopped()) {
> return cleanSetOfActiveMaster;
> }
> // Try to become active master again now that there is no active master
> blockUntilBecomingActiveMaster(startupStatus,clusterStatusTracker);
> }
> return cleanSetOfActiveMaster;
> {code}
> When the back up master (it is in back up mode as he got ZK exception), once
> again tries to come to active we don't get the return value that comes out
> from
> {code}
> // Try to become active master again now that there is no active master
> blockUntilBecomingActiveMaster(startupStatus,clusterStatusTracker);
> {code}
> We tend to return the 'cleanSetOfActiveMaster' which was previously false.
> Now because of this instead of again becoming active the back up master goes
> down in the abort() code. Thanks to Gopi,my colleague for reporting this
> issue.
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