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From "stack (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-5155) ServerShutDownHandler And Disable/Delete should not happen parallely leading to recreation of regions that were deleted
Date Wed, 11 Jan 2012 06:12:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-5155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13183898#comment-13183898
] 

stack commented on HBASE-5155:
------------------------------

Ugh, I wrote a comment and lost it.

So, when you say above that '-> The tables and its regions are deleted including R1, D1
and D2.. (So META is cleaned)', you are saying that this happens AFTER SSH has scanned .META.
and that we're doing the region processing AFTER the deletes (I was going to say its odd that
we fixup a daughter when parent is missing but checking .META. and filesystem before each
daughter fixup would still have a hole during which a delete could come in....)

On keeping a TableState.ENABLED up in zk, that could work (Can't remember why didn't do it
that way originally -- only thought is that was trying to save on the state kept up in zk
which is a pretty pathetic reason).  You'll need to add an AM.isEnabledTable method to match
the isDisabledTable, etc., stuff that is already there.  Good stuff Ram.
                
> ServerShutDownHandler And Disable/Delete should not happen parallely leading to recreation
of regions that were deleted
> -----------------------------------------------------------------------------------------------------------------------
>
>                 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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