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From Koji Noguchi <knogu...@yahoo-inc.com>
Subject Re: namenode grows overtime
Date Fri, 20 Jan 2012 19:57:04 GMT
Felix, if no options are specified, then I think what Harsh said makes most sense.


> Felix,
> Are you noticing this from the NN Web UI or from proper JVM monitoring
> tools? Just so you know, the UI had a flaw that has since been fixed:
> https://issues.apache.org/jira/browse/HDFS-94
> --
> Harsh J
> Customer Ops. Engineer, Cloudera

On 1/20/12 1:25 AM, "Uma Maheswara Rao G" <maheswara@huawei.com> wrote:

Can you please check in UI, what is the heap usage. Then we can confirm whether java heap
is growing or not.

top will consider native memory usage also and nio uses directByteBuffers internally.

This is good write up from Jonathan https://groups.google.com/group/asynchbase/browse_thread/thread/c45bc7ba788b2357



From: felix gao [gre1600@gmail.com]
Sent: Friday, January 20, 2012 6:42 AM
To: hdfs-user@hadoop.apache.org
Subject: Re: namenode grows overtime


There is no Java options specified other than -Xmx24g, what are some of the recommended options
for namenode?



On Wed, Jan 18, 2012 at 3:39 PM, Koji Noguchi <knoguchi@yahoo-inc.com> wrote:
Hi Felix,

Taking  jmap –histo:live <pid> would tell you what’s occupying the heap.

Are you using  UseConcMarkSweepGC?
If yes, and if you see bunch of
from jmap histo outputs, try passing    -XX:-CMSConcurrentMTEnabled .

Background: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7113118


On 1/18/12 3:23 PM, "felix gao" <gre1600@gmail.com <http://gre1600@gmail.com> >

Hi guys,

we are running Hadoop 0.20.2+228, the namenode process's memory grows overtime to occupy over
18GB.  However, if I restart the namenode, it only occupies about 10GB after it is stable.
 I am wondering if there is anyway to figure out what is going on with namenode that causes
it to grow very rapidly and if there are any tools to make the namenode printout some useful
information on what is holding onto that memory.



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