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Date: Mon, 9 Jan 2012 13:18:40 +0000 (UTC)
From: "ramkrishna.s.vasudevan (Created) (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Created] (HBASE-5155) ServerShutDownHandler And
 Disable/Delete should not happen parallely leading to recreation of regions
 that were deleted
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ServerShutDownHandler And Disable/Delete should not happen parallely leading to recreation of regions that were deleted
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                 Key: HBASE-5155
                 URL: https://issues.apache.org/jira/browse/HBASE-5155
             Project: HBase
          Issue Type: Bug
          Components: master
    Affects Versions: 0.90.4
            Reporter: ramkrishna.s.vasudevan
            Priority: Blocker


ServerShutDownHandler and disable/delete table handler races.  This is not an issue due to TM.
-> A regionserver goes down.  In our cluster the regionserver holds lot of regions.
-> A region R1 has two daughters D1 and D2.
-> The ServerShutdownHandler gets called and scans the META and gets all the user regions
-> Parallely a table is disabled. (No problem in this step).
-> Delete table is done.
-> The tables and its regions are deleted including R1, D1 and D2.. (So META is cleaned)
-> Now ServerShutdownhandler starts to processTheDeadRegion
{code}
 if (hri.isOffline() && hri.isSplit()) {
      LOG.debug("Offlined and split region " + hri.getRegionNameAsString() +
        "; checking daughter presence");
      fixupDaughters(result, assignmentManager, catalogTracker);
{code}
As part of fixUpDaughters as the daughers D1 and D2 is missing for R1 
{code}
    if (isDaughterMissing(catalogTracker, daughter)) {
      LOG.info("Fixup; missing daughter " + daughter.getRegionNameAsString());
      MetaEditor.addDaughter(catalogTracker, daughter, null);

      // TODO: Log WARN if the regiondir does not exist in the fs.  If its not
      // there then something wonky about the split -- things will keep going
      // but could be missing references to parent region.

      // And assign it.
      assignmentManager.assign(daughter, true);
{code}
we call assign of the daughers.  
Now after this we again start with the below code.
{code}
        if (processDeadRegion(e.getKey(), e.getValue(),
            this.services.getAssignmentManager(),
            this.server.getCatalogTracker())) {
          this.services.getAssignmentManager().assign(e.getKey(), true);
{code}
Now when the SSH scanned the META it had R1, D1 and D2.
So as part of the above code D1 and D2 which where assigned by fixUpDaughters
is again assigned by 
{code}
this.services.getAssignmentManager().assign(e.getKey(), true);
{code}
Thus leading to a zookeeper issue due to bad version and killing the master.
The important part here is the regions that were deleted are recreated which i think is more critical.

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