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Posted to users@tomcat.apache.org by msweeney <wh...@gmail.com> on 2009/05/28 14:50:52 UTC
Centos 5 OS not releasing memory Tomcat6
Tomcat version 6
Apache 2.2.3
Centos 5.2
VMware 2.5
2 VPU's
4G Memory
Guest Memory usage is on a avg 122 MB and Host Memory is at 3.31 G so we
know it's not the balloon driver.
Problem statement:
I understand as a SysAdmin that the JVM loves to grab all the memory
resources as it can, sort of like Oracle. However when we stop and then
attempt to restart Tomcat it fails and the server needs to be restarted.
Also it seems that this memory is being held in the Linux Cache system and
to release it we run the following:
echo 3 > /proc/sys/vm/drop_caches
I guess my question is there a tuneable on either the OS or in the JVM that
will give me the same result?
Let me know any more information I need to provide.
Thanks,
Marc Sweeney
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by Christopher Schultz <ch...@christopherschultz.net>.
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Marc,
You haven't yet provided any proof that any memory (at all) is allocated
to "Tomcat 6". Could you maybe show us some output of "top" or "ps" or
something like that?
If you're convinced that it's an OS problem, why not ask someone at CentOS?
- -chris
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by msweeney <wh...@gmail.com>.
Here's the /etc/sysctl.conf parameters that I've started with:
vm.dirty_writeback_centisecs = 100
vm.dirty_expire_centisecs = 100
vm.pagecache = 1 10 30
Since this server is taking Production traffic, we'll need to what for a
window to test this. I'll let you know how it works out. If the two
vm.dirty don't correct it I'll take it down to 0 for I believe the CPU's
will be able to handle the extra cycles.
Regards,
Marc
Maurizio Rottin wrote:
>
> 2009/5/28 André Warnier <aw...@ice-sa.com>:
>> If a non-existent process is able to hold on to some memory and not
>> return
>> it to the OS, doesn't that indicate an OS problem ?
>
> i think so!
> but i do not remeber any kernel problem related to memory caching in
> Centos kernel releases.
>
> Maybe you should give a try at Centos 5.3 kernels.
>
> --
> mr
>
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by Maurizio Rottin <ma...@gmail.com>.
2009/5/28 André Warnier <aw...@ice-sa.com>:
> If a non-existent process is able to hold on to some memory and not return
> it to the OS, doesn't that indicate an OS problem ?
i think so!
but i do not remeber any kernel problem related to memory caching in
Centos kernel releases.
Maybe you should give a try at Centos 5.3 kernels.
--
mr
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by André Warnier <aw...@ice-sa.com>.
msweeney wrote:
> Hi,
>
> Thank you for your reply.
>
> Yes we did a custom install on Tomcat6.
>
> No there wasn't any java processes running when we stopped Tomcat, so it
> appears from the OS level to be shutting down, but it's not releasing the
> memory space back to the OS.
>
If a non-existent process is able to hold on to some memory and not
return it to the OS, doesn't that indicate an OS problem ?
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by msweeney <wh...@gmail.com>.
Hi,
Thank you for your reply.
Yes we did a custom install on Tomcat6.
No there wasn't any java processes running when we stopped Tomcat, so it
appears from the OS level to be shutting down, but it's not releasing the
memory space back to the OS.
running the free command after stopping Tomcat shows all the memory still
being held:
# free
total used free shared buffers cached
Mem: 3921884 3326672 595212 0 317044 1528544
-/+ buffers/cache: 1481084 2440800
Swap: 2048152 316244 1731908
What I'm doing now is looking into the sysctl.conf parameters that will
flush the cache, sort of like Oracle.
Regards,
Marc Sweeney
Maurizio Rottin wrote:
>
> 2009/5/28 msweeney <wh...@gmail.com>:
>>
>> Tomcat version 6
>> Apache 2.2.3
>> Centos 5.2
>> VMware 2.5
>> 2 VPU's
>> 4G Memory
>>
>> Guest Memory usage is on a avg 122 MB and Host Memory is at 3.31 G so we
>> know it's not the balloon driver.
>>
>> Problem statement:
>>
>> I understand as a SysAdmin that the JVM loves to grab all the memory
>> resources as it can, sort of like Oracle. However when we stop and then
>> attempt to restart Tomcat it fails and the server needs to be restarted.
>> Also it seems that this memory is being held in the Linux Cache system
>> and
>> to release it we run the following:
>> echo 3 > /proc/sys/vm/drop_caches
>
> tomcat6 is not included in Centos, then i assume you take source file
> from apache tomcat website.
>
> If this is the case, when you stop tomcat, then you have to kill the
> process.
> try a "ps -ef | grep j" and you will probably see that java is still
> running.
>
> if you are succesful in killing the process, then try to start tomcat.
>
> --
> mr
>
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>
>
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Re: Centos 5 OS not releasing memory Tomcat6
Posted by Maurizio Rottin <ma...@gmail.com>.
2009/5/28 msweeney <wh...@gmail.com>:
>
> Tomcat version 6
> Apache 2.2.3
> Centos 5.2
> VMware 2.5
> 2 VPU's
> 4G Memory
>
> Guest Memory usage is on a avg 122 MB and Host Memory is at 3.31 G so we
> know it's not the balloon driver.
>
> Problem statement:
>
> I understand as a SysAdmin that the JVM loves to grab all the memory
> resources as it can, sort of like Oracle. However when we stop and then
> attempt to restart Tomcat it fails and the server needs to be restarted.
> Also it seems that this memory is being held in the Linux Cache system and
> to release it we run the following:
> echo 3 > /proc/sys/vm/drop_caches
tomcat6 is not included in Centos, then i assume you take source file
from apache tomcat website.
If this is the case, when you stop tomcat, then you have to kill the process.
try a "ps -ef | grep j" and you will probably see that java is still running.
if you are succesful in killing the process, then try to start tomcat.
--
mr
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