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https://issues.apache.org/jira/browse/HBASE-6289?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403307#comment-13403307
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stack commented on HBASE-6289:
------------------------------
bq. Any specific reason why we are verifying and then assigning the root region
alone?
Are you asking why we assign the root, then the meta, ahead of all other
assignments? If so, its because these need to be assigned for sure before any
other assignments will complete. Maybe you were asking something else?
@Ted A test would be hard to get in here methinks for the startup code. Would
take a bunch of mocking. We, the hbase core, should make it easier on folks
mocking up these scenarios by building the necessary underpinnings before we
can expect the likes of Maryann to deliver a unit test (thats my opinion).
> 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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