[Users] memory issues

[Daniel-Constantin Mierla]

On 03/18/07 23:09, Christian Schlatter wrote:
> Daniel-Constantin Mierla wrote:
>> Hello,
>>
>> that's the result of memory fragmentations, that should be the the 
>> capacity of the server, should stay at that rate. Memory manager 
>> allocates chunks of different sizes, but not merges then back by 
>> default. However, it tries to avoid allocating small sizes -- you can 
>> see in statistics used memory and real used sizes. The difference is 
>> not used but should ensure that shared variables will not fragment 
>> memory in small chunks.
>
> The memory statistics indeed show a high number of memory fragments:
>
> before 'out of memory':
>
> shmem:total_size = 536870912
> shmem:used_size = 59607040
> shmem:real_used_size = 60106488
> shmem:max_used_size = 68261536
> shmem:free_size = 476764424
> shmem:fragments = 9897
>
> after 'out of memory' (about 8000 calls per process):
>
> shmem:total_size = 536870912
> shmem:used_size = 4171160
> shmem:real_used_size = 4670744
> shmem:max_used_size = 68261536
> shmem:free_size = 532200168
> shmem:fragments = 57902
>
>>
>> You can try to compile openser with -DQM_JOIN_FREE (add it in DEFS 
>> variable of Makefile.defs) and test again. Free fragments should be 
>> merged and fragmentation should not occur -- processing will be 
>> slower. We will try for next release to provide a better solution for 
>> that.
>
> Compiling openser with -DQM_JOIN_FREE did not help. I'm not sure how 
> big of a problem this fragmentation issue is.
What is the number of fragments with QM_JOIN_FREE after flooding?
> Do you think it would make sense to restart our production openser 
> instances from time to time just to make sure they're not running into 
> this memory fragmentation limits?
The issue will occur only when the call rate reaches the limits of the 
proxy's memory. Otherwise the chunks are reused. Transactions and avps 
are rounded up to be sure there will be minimized the number of 
different sizes for memory chunks. It wasn't reported too often, maybe 
that's why no big attention was paid to it. This memory system is in 
place since the beginning of ser. Alternative is to use sysv shared 
memory, but is much slower, along with libc private memory manager.

Cheers,
Daniel

>
> thanks,
> Christian
>
>>
>> Cheers,
>> Daniel
>>
>> On 03/18/07 01:21, Christian Schlatter wrote:
>>> Christian Schlatter wrote:
>>> ...
>>>>
>>>> I always had 768MB shared memory configured though, so I still 
>>>> can't explain the memory allocation errors I got. Some more test 
>>>> runs revealed that I only get these errors when using a more 
>>>> production oriented config that loads more modules than the one 
>>>> posted in my earlier email. I now try to figure out what exactly 
>>>> causes these memory allocation errors that happen reproducibly 
>>>> after about 220s at 400 cps.
>>>
>>> I think I found the cause for the memory allocation errors. As soon 
>>> as I include an AVP write operation in the routing script, I get 
>>> 'out of memory' messages after a certain number of calls generated 
>>> with sipp.
>>>
>>> The routing script to reproduce this behavior looks like (full 
>>> config available at http://www.unc.edu/~cschlatt/openser/openser.cfg):
>>>
>>> route{
>>>         $avp(s:ct) = $ct; # commenting this line solves
>>>               # the memory problem
>>>
>>>         if (!method=="REGISTER") record_route();
>>>         if (loose_route()) route(1);
>>>
>>>         if (uri==myself) rewritehost("xx.xx.xx.xx");
>>>         route(1);
>>> }
>>>
>>> route[1] {
>>>         if (!t_relay()) sl_reply_error();
>>>         exit;
>>> }
>>>
>>> An example log file showing the 'out of memory' messages is 
>>> available at http://www.unc.edu/~cschlatt/openser/openser.log .
>>>
>>> Some observations:
>>>
>>> - The 'out of memory' messages always appear after about 8000 test 
>>> calls per worker process. One call consists of two SIP transactions 
>>> and six end-to-end SIP messages. An openser with 8 children handles 
>>> about 64'000 calls, whereas 4 children only handle about 32'000 
>>> calls. The sipp call rate doesn't matter, only number of calls.
>>>
>>> - The 8000 calls per worker process are independent from the amount 
>>> of shared memory available. Running openser with -m 128 or -m 768 
>>> does not make a difference.
>>>
>>> - The more AVP writes are done in the script, the less calls go 
>>> through. It looks like each AVP write is leaking memory (unnoticed 
>>> by the memory statistics).
>>>
>>> - The fifo memory statistics do not reflect the 'out of memory' 
>>> syslog messages. Even if openser does not route a single SIP message 
>>> because of memory issues, the statistics still show a lot of 'free' 
>>> memory.
>>>
>>>
>>> All tests were done with openser SVN 1.2 branch on Ubuntu dapper 
>>> x86. I think the same is true for 1.1 version but I haven't tested 
>>> that yet.
>>>
>>>
>>> Christian
>>>
>
>