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From "Jonathan Gray" <jg...@apache.org>
Subject Re: Review Request: Stale reads from ZK can break the atomic CAS operations we have in ZKAssign
Date Thu, 21 Oct 2010 00:24:12 GMT


> On 2010-10-20 16:49:52, Todd Lipcon wrote:
> > seems OK, but we're adding couple extra ms of latency here on all of these calls.
Is that going to be expensive for assigning lots of regions?
> > It seems we should be optimistic, and only really need to sync if we see unexpected
state or the checked put fails?

Yeah, gave that a quick shot.  It's not easy (the code gets messy quick so it needs to be
well thought out).

I'd like to commit this and we can open another jira to deal with the optimistic approach.


- Jonathan


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This is an automatically generated e-mail. To reply, visit:
http://review.cloudera.org/r/1056/#review1590
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On 2010-10-20 16:47:05, Jonathan Gray wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://review.cloudera.org/r/1056/
> -----------------------------------------------------------
> 
> (Updated 2010-10-20 16:47:05)
> 
> 
> Review request for hbase, Todd Lipcon and stack.
> 
> 
> Summary
> -------
> 
> Adds a sync(path) operation into ZKW and three calls into it from the CAS operations
in ZKAssign.
> 
> 
> This addresses bug HBASE-3136.
>     http://issues.apache.org/jira/browse/HBASE-3136
> 
> 
> Diffs
> -----
> 
>   trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKAssign.java 1025790 
>   trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java 1025790

> 
> Diff: http://review.cloudera.org/r/1056/diff
> 
> 
> Testing
> -------
> 
> Still need to test more.  I'm not sure it's possible (or feasible in a reasonable amount
of time) to make a unit test for this.  We'd probably need to dig into ZK or mock the hell
out of stuff.
> 
> 
> Thanks,
> 
> Jonathan
> 
>


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