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From Ted Yu <yuzhih...@gmail.com>
Subject Re: How to know the root reason to cause RegionServer OOM?
Date Wed, 20 May 2015 09:58:12 GMT
For scenario #1, please check regionserver.out file - not log file. 

I was able to reproduce scenario #1 by giving regionserver 124mb heap. As soon as I put load
on the server, server was killed by "kill -9" command. 

I can send you snippet from .out file in the morning. 

Cheers



> On May 20, 2015, at 1:46 AM, David chen <c77_cn@163.com> wrote:
> 
> Thanks Ted,
> For scenario #1, can not see any clues in regionserver log file that denotes "kill -9"
command was executed. Meanwhile, i think when JVM inspects regionserver process OOME, it will
create a new thread to execute "kill -9 %p", the new thread should not write regionserver
log, so the fact, there is not any clues in regionserver log, is normal. Right?
> For scenario #2, dmesg also did not provide any clues. But some clues were seen in /var/log/messages:
> ......
> May 14 12:00:38 localhost kernel: Out of memory: Kill process 22827 (java) score 497
or sacrifice child
> May 14 12:00:38 localhost kernel: Killed process 22827, UID 483, (java) total-vm:17569220kB,
anon-rss:16296276kB, file-rss:240kB
> ......
> The 22827 above is regionserver PID.
> It looks like regionserver itself OOM(total-vm:17569220kB, anon-rss:16296276kB, the max-heap-size
set is 15G), so was killed. Right?
> But hbase has no heavy load in the cluster, so i don't think it was killed because of
itself OOME, instead i think because of lack of memory for other applications, so OS kill
regionserver to run more applications. 
> I currently has no evidence to prove my idea, so hope more helps. Thanks.
> 
> 
> 
> 
> 
> 
> 
> 
> At 2015-05-20 10:04:19, "Ted Yu" <yuzhihong@gmail.com> wrote:
>> For scenario #1, you would see in the regionserver.out file that "kill -9 "
>> command was applied due to OOME.
>> 
>> For scenario #2, can you see if dmesg provides some clue ?
>> 
>> Cheers
>> 
>>> On Tue, May 19, 2015 at 6:32 PM, David chen <c77_cn@163.com> wrote:
>>> 
>>> Thanks for guys reply, its indeed helped me.
>>> Another question, I think there are two possibilities to kill RegionServer
>>> process:
>>> 1. When JVM inspects that the memory, RegionServer has occupied, exceed
>>> the max-heap-size,  then JVM calls positively the command configured by
>>> option "-XX:OnOutOfMemoryError=kill -9 %p" to kill RegionServer  process.
>>> 2. RegionServer process does not reach the max-heap-size, but new
>>> application need to allocation memory,  if lack of memory, OS will choose
>>> to kill some processes, RegionServer unfortunately becomes the first
>>> choice, so it  is killed by OS.
>>> Is my understanding right? If so, how to know which possibility my scene
>>> is?
>>> Any ideas can be appreciated!
>>> 

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