[jira] [Commented] (HBASE-15251) During a cluster restart, Hmaster thinks it is a failover by mistake

["Ted Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-15251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15143717#comment-15143717 ] 

Ted Yu commented on HBASE-15251:
--------------------------------

Looks good overall.
{code}
447	      // Check if there are any regions on these servers
448	      failover = false;
{code}
failover is false coming to line 448, there is no need to set to false again.
{code}
465	          LOG.debug("Found region" + hri + " out on cluster");
{code}
Leave out a space between region and hri in the output.
{code}
574	    if (!fs.getFileStatus(dir).isDirectory()) {
575	      LOG.warn(dir + " is not a directory");
{code}
I think the warn() should be debug().
{code}
584	      if (files[i].isFile() && files[i].getLen() > 0) {
585	        LOG.debug(dir + " has a non-empty file: " + files[i].getPath());
{code}
For file, the above log is inaccurate.

> During a cluster restart, Hmaster thinks it is a failover by mistake
> --------------------------------------------------------------------
>
>                 Key: HBASE-15251
>                 URL: https://issues.apache.org/jira/browse/HBASE-15251
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>    Affects Versions: 2.0.0, 0.98.15
>            Reporter: Clara Xiong
>            Assignee: Clara Xiong
>         Attachments: HBASE-15251-master.patch
>
>
> We often need to do cluster restart as part of release for a cluster of > 1000 nodes. We have tried our best to get clean shutdown but 50% of the time, hmaster still thinks it is a failover. This increases the restart time from 5 min to 30 min and decreases locality from 99% to 5% since we didn't use a locality-aware balancer. We had a bug HBASE-14129 but the fix didn't work. 
> After adding more logging and inspecting the logs, we identified two things that trigger the failover handling:
> 1.  When Hmaster.AssignmentManager detects any dead servers on service manager during joinCluster(), it determines this is a failover without further check. I added a check whether there is even any region assigned to these servers. During a clean restart, the regions are not even assigned.
> 2. When there are some leftover empty folders for log and split directories or empty wal files, it is also treated as a failover. I added a check for that. Although this can be resolved by manual cleanup, it is still too tedious for restarting a large cluster.
> Patch will follow shortly. The fix is tested and used in production now.



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