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https://issues.apache.org/jira/browse/HBASE-3362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12972331#action_12972331
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HBase Review Board commented on HBASE-3362:
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Message from: "Jonathan Gray" <[email protected]>
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Ship it!
it's getting pretty crazy but this looks good.
it's unfortunate we have all these extra node transitioning methods inside this
class. this pattern of doing node transitions and tracking expected version is
very common and we'll probably have more of it so we should look at doing some
kind of generic abstraction for that pattern soon.
+1 for commit, thanks for the changes
trunk/src/main/java/org/apache/hadoop/hbase/regionserver/handler/OpenRegionHandler.java
<http://review.cloudera.org/r/1298/#comment6561>
typo 'initalizes' but good comment
trunk/src/main/java/org/apache/hadoop/hbase/regionserver/handler/OpenRegionHandler.java
<http://review.cloudera.org/r/1298/#comment6562>
interesting thing is... we only use this progressable if we do a log
replay. in that case, a region open is not really idempotent as we treat it
here.
outside scope of this jira but something to think about.
- Jonathan
> If .META. offline between OPENING and OPENED, then wrong server location in
> .META. is possible
> ----------------------------------------------------------------------------------------------
>
> Key: HBASE-3362
> URL: https://issues.apache.org/jira/browse/HBASE-3362
> Project: HBase
> Issue Type: Bug
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Fix For: 0.90.0
>
>
> This is a good one. It happened to me testing OOME in split logging.
> * Balancer moves region to new location, regionservrer X.
> * New location regionserver X successfully opens the region and then goes to
> update .META.
> * At this point, the server carrying .META. crashes.
> * Regionserver X is stuck waiting on .META. to come back online. It takes so
> long master times out the region-in-transition
> * Master assigns the region elsewhere to regionserver Y
> * It opens successfully on regionserver Y and then it also parks waiting on
> .META. coming online
> * .META. comes online
> * The two servers X and Y race to update .META.
> I saw case where server X edit went in after server Ys edit which means that
> lookups in .META. get the wrong server. HBCK can detect this situation.
> RegionServer X when it wakes up coreeclty notices that its lost control of
> the region but the damage is done -- where damage is .META. edit.
> Chatting with Jon, he suggested that regionserver X should 'rollback' the
> .META. edit -- do explicit delete of what it added. This would work I think
> but chatting more, I'll make a fix that keeps updating the zookeeper OPENING
> state while edit goes on in a separate thread. Our continuous setting of
> OPENING will make it so region-in-transition does not timeout.
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