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From Adam Faris <afa...@linkedin.com>
Subject Re: NN Memory Jumps every 1 1/2 hours
Date Sat, 22 Dec 2012 04:59:07 GMT
I know this will sound odd, but try reducing your heap size.   We had an issue like this where
GC kept falling behind and we either ran out of heap or would be in full gc.  By reducing
heap, we were forcing concurrent mark sweep to occur and avoided both full GC and running
out of heap space as the JVM would collect objects more frequently.  

On Dec 21, 2012, at 8:24 PM, Edward Capriolo <edlinuxguru@gmail.com> wrote:

> I have an old hadoop 0.20.2 cluster. Have not had any issues for a while.
> (which is why I never bothered an upgrade)
> Suddenly it OOMed last week. Now the OOMs happen periodically. We have a
> fairly large NameNode heap Xmx 17GB. It is a fairly large FS about
> 27,000,000 files.
> So the strangest thing is that every 1 and 1/2 hour the NN memory usage
> increases until the heap is full.
> http://imagebin.org/240287
> We tried failing over the NN to another machine. We change the Java version
> from 1.6_23 -> 1.7.0.
> I have set the NameNode logs to debug and ALL and I have done the same with
> the data nodes.
> Secondary NN is running and shipping edits and making new images.
> I am thinking something has corrupted the NN MetaData and after enough time
> it becomes a time bomb, but this is just a total shot in the dark. Does
> anyone have any interesting trouble shooting ideas?

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