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From Michael Segel <michael_se...@hotmail.com>
Subject Re: NN Memory Jumps every 1 1/2 hours
Date Sat, 22 Dec 2012 15:42:58 GMT
Hey Silly question... 

How long have you had 27 million files? 

I mean can you correlate the number of files to the spat of OOMs? 

Even without problems... I'd say it would be a good idea to upgrade due to the probability
of a lot of code fixes... 

If you're running anything pre 1.x, going to 1.7 java wouldn't be a good idea.  Having said
that... outside of MapR, have any of the distros certified themselves on 1.7 yet? 

On Dec 22, 2012, at 6:54 AM, Edward Capriolo <edlinuxguru@gmail.com> wrote:

> I will give this a go. I have actually went in JMX and manually triggered
> GC no memory is returned. So I assumed something was leaking.
> On Fri, Dec 21, 2012 at 11:59 PM, Adam Faris <afaris@linkedin.com> wrote:
>> 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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