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From Gaojinchao <gaojinc...@huawei.com>
Subject FeedbackRe: Suspected memory leak
Date Sun, 04 Dec 2011 03:57:58 GMT
Thank you for your help.

This issue appears to be a configuration problem:
1. HBase client uses NIO(socket) API that uses the direct memory.
2. Default -XXMaxDirectMemorySize value is equal to -Xmx value, So if there doesn't have "full
gc", all direct memory can't reclaim. Unfortunately, using GC confiugre parameter of our client
doesn't produce any "full gc".
This is only a preliminary result,  All tests is running, If have any further results , we
will be fed back.
Finally , I will update our story to issue https://issues.apache.org/jira/browse/HBASE-4633.

If our digging is crrect, whether we should set a default value for the "-XXMaxDirectMemorySize"
to prevent this situation?


发件人: bijieshan [mailto:bijieshan@huawei.com] 
发送时间: 2011年12月2日 15:37
收件人: dev@hbase.apache.org; user@hbase.apache.org
抄送: Chenjian; wenzaohua
主题: Re: Suspected memory leak

Thank you all. 
I think it's the same problem with the link provided by Stack. Because the heap-size is stabilized,
but the non-heap size keep growing. So I think not the problem of the CMS GC bug. 
And we have known the content of the problem memory section, all the records contains the
info like below:


发件人: Kihwal Lee [mailto:kihwal@yahoo-inc.com] 
发送时间: 2011年12月2日 4:20
收件人: dev@hbase.apache.org
抄送: Ramakrishna s vasudevan; user@hbase.apache.org
主题: Re: Suspected memory leak

Adding to the excellent write-up by Jonathan:
Since finalizer is involved, it takes two GC cycles to collect them.  Due to a bug/bugs in
the CMS GC, collection may not happen and the heap can grow really big.  See http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7112034
for details.

Koji tried "-XX:-CMSConcurrentMTEnabled" and confirmed that all the socket related objects
were being collected properly. This option forces the concurrent marker to be one thread.
This was for HDFS, but I think the same applies here.


On 12/1/11 1:26 PM, "Stack" <stack@duboce.net> wrote:

Make sure its not the issue that Jonathan Payne identifiied a while
back: https://groups.google.com/group/asynchbase/browse_thread/thread/c45bc7ba788b2357#

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