[horde] Too many httpd processes and no response

[lst_hoe02 at kwsoft.de]

Zitat von Arjen de Korte <arjen+horde at de-korte.org>:

> Citeren ANANT S ATHAVALE <asa at isac.gov.in>:
>
>> ----- Message from Arjen de Korte <arjen+horde at de-korte.org> ---------
>>    Date: Tue, 14 Jan 2014 09:58:43 +0100
>>    From: Arjen de Korte <arjen+horde at de-korte.org>
>> Subject: Re: [horde] Too many httpd processes and no response
>>      To: horde at lists.horde.org
>>
>>> Citeren ANANT S ATHAVALE <asa at isac.gov.in>:
>>>
>>>> ----- Message from Arjen de Korte <arjen+horde at de-korte.org> ---------
>>>>    Date: Mon, 13 Jan 2014 15:52:03 +0100
>>>>    From: Arjen de Korte <arjen+horde at de-korte.org>
>>>> Subject: Re: [horde] Too many httpd processes and no response
>>>>      To: horde at lists.horde.org
>>>>
>>>>> Citeren ANANT S ATHAVALE <asa at isac.gov.in>:
>>>>>
>>>>>> Dear List,
>>>>>>
>>>>>> I have released HGWE 5.1.3 to my users from last 3 days.
>>>>>>
>>>>>> We are facing unusual problem.
>>>>>>
>>>>>> When there is not much load, there is no problem at all.
>>>>>>
>>>>>> But, during peak hours of usage on a working day, suddenly too many
>>>>>> httpd
>>>>>> processes start and user gets no response.  Only solution is to restart
>>>>>> httpd.  By this, there won't any issue for atleast one hour and problem
>>>>>> repeats.
>>>>>
>>>>> My first guess would be that you allow your server to spawn too many
>>>>> processes to serve the incoming requests. If this is more than the
>>>>> amount of memory allows, the result will be swapping and a dramatic
>>>>> decrease in performance. Users will try to reconnect then, worsening the
>>>>> problem. Which webserver are you using? If Apache, which MPM are you
>>>>> using?
>>>>
>>>> Using Apache.  prefork MPM.  Default, as provided by RHEL.
>>>
>>> What is the average process size of Apache? You may need to change
>>> 'httpd' in the below to whatever RHEL is using:
>>>
>>> ps -ylC httpd | awk '{x += $8;y += 1} END {print "Apache Memory Usage
>>> (MB): "x/1024; print "Average Proccess Size (MB): "x/((y-1)*1024)}'
>>
>> This is what I got on a minimal load condition. 
>> Apache Memory Usage (MB): 1651.5
>> Average Process Size (MB): 63.5191
>
> That's a process size about what I would expect for a system running  
> Horde. You'll want to keep an eye on these figures when the load is  
> higher too.

 From what i know this numbers are far too high because they don't  
account for "shared text", no?
The process size include all kind of code pages which are only loaded  
once and shared by all processes with the same user context  
(http://virtualthreads.blogspot.de/2006/02/understanding-memory-usage-on-linux.html).
So the memmory demand per additional process is much lower, taken code  
needed is already loaded at least once.
For more precise numbers one have to examine a process with pmap and  
add the none "anon" rw segments and the stack IMHO.

Regards

Andreas