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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 00:41:58 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?
> 
> Jonathan Gray wrote:
>     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.
> 
> Todd Lipcon wrote:
>     OK, that sounds good by me. We'll fix the perf issue in a follow-up.
>     
>     Would still like Stack to review, I don't know the master code well enough to know
if any other places might be missing, but I agree in concept :)

Cool.  I'm kicking off a test suite run with this patch and my hbck patch right now as well.

HBASE-3137 filed for perf improvements.


- Jonathan


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
http://review.cloudera.org/r/1056/#review1590
-----------------------------------------------------------


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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