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Date: Thu, 28 Jun 2012 17:36:44 +0000 (UTC)
From: "Zhihong Ted Yu (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Updated] (HBASE-6289) ROOT region doesn't get re-assigned
 in ServerShutdownHandler if the RS is still working but only the RS's ZK
 node expires.
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     [ https://issues.apache.org/jira/browse/HBASE-6289?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhihong Ted Yu updated HBASE-6289:
----------------------------------

    Description: 
The ROOT RS has some network problem and its ZK node expires first, which kicks off the ServerShutdownHandler. it calls verifyAndAssignRoot() to try to re-assign ROOT. At that time, the RS is actually still working and passes the verifyRootRegionLocation() check, so the ROOT region is skipped from re-assignment.
{code}
  private void verifyAndAssignRoot()
  throws InterruptedException, IOException, KeeperException {
    long timeout = this.server.getConfiguration().
      getLong("hbase.catalog.verification.timeout", 1000);
    if (!this.server.getCatalogTracker().verifyRootRegionLocation(timeout)) {
      this.services.getAssignmentManager().assignRoot();
    }
  }
{code}
After a few moments, this RS encounters DFS write problem and decides to abort. The RS then soon gets restarted from commandline, and constantly report:
{code}
2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,630 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
{code}

  was:
The ROOT RS has some network problem and its ZK node expires first, which kicks off the ServerShutdownHandler. it calls verifyAndAssignRoot() to try to re-assign ROOT. At that time, the RS is actually still working and passes the verifyRootRegionLocation() check, so the ROOT region is skipped from re-assignment.
  private void verifyAndAssignRoot()
  throws InterruptedException, IOException, KeeperException {
    long timeout = this.server.getConfiguration().
      getLong("hbase.catalog.verification.timeout", 1000);
    if (!this.server.getCatalogTracker().verifyRootRegionLocation(timeout)) {
      this.services.getAssignmentManager().assignRoot();
    }
  }

After a few moments, this RS encounters DFS write problem and decides to abort. The RS then soon gets restarted from commandline, and constantly report:
2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
2012-06-27 23:13:08,630 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0


> ROOT region doesn't get re-assigned in ServerShutdownHandler if the RS is still working but only the RS's ZK node expires.
> --------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-6289
>                 URL: https://issues.apache.org/jira/browse/HBASE-6289
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>    Affects Versions: 0.90.6, 0.94.0
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>            Priority: Critical
>         Attachments: HBASE-6289.patch
>
>
> The ROOT RS has some network problem and its ZK node expires first, which kicks off the ServerShutdownHandler. it calls verifyAndAssignRoot() to try to re-assign ROOT. At that time, the RS is actually still working and passes the verifyRootRegionLocation() check, so the ROOT region is skipped from re-assignment.
> {code}
>   private void verifyAndAssignRoot()
>   throws InterruptedException, IOException, KeeperException {
>     long timeout = this.server.getConfiguration().
>       getLong("hbase.catalog.verification.timeout", 1000);
>     if (!this.server.getCatalogTracker().verifyRootRegionLocation(timeout)) {
>       this.services.getAssignmentManager().assignRoot();
>     }
>   }
> {code}
> After a few moments, this RS encounters DFS write problem and decides to abort. The RS then soon gets restarted from commandline, and constantly report:
> {code}
> 2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
> 2012-06-27 23:13:08,627 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
> 2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
> 2012-06-27 23:13:08,628 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
> 2012-06-27 23:13:08,630 DEBUG org.apache.hadoop.hbase.regionserver.HRegionServer: NotServingRegionException; Region is not online: -ROOT-,,0
> {code}

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