[horde] Too many httpd processes and no response

[ANANT S ATHAVALE]

  ----- Message from ANANT S ATHAVALE <asa at isac.gov.in> ---------
   Date: Tue, 14 Jan 2014 19:32:09 +0530
   From: ANANT S ATHAVALE <asa at isac.gov.in>
Subject: ***SPAM-UTM*** Re: [horde] Too many httpd processes and no
response
     To: horde at lists.horde.org

> ----- Message from Arjen de Korte <arjen+horde at de-korte.org> ---------
>    Date: Tue, 14 Jan 2014 13:49:41 +0100
>    From: Arjen de Korte <arjen+horde at de-korte.org>
> Subject: ***SPAM-UTM*** 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: 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.
>>
>> OK.
>>
>>>> Make sure that the server is actually under load, to make sure the
>>>> process sizes reported are representative. If the average process size
>>>> multiplied by the value of MaxClients in your apache configuration is
>>>> more than about 75-80% of the memory in the system, you're just
waiting
>>>> for a disaster to happen sooner or later.
>>>
>>> As per this, I should not have MaxClients somewhere around 400 or even
>>> lesser.  Please correct me, if I am wrong.
>>
>> Assuming that the amount of free memory (without Apache running) would
>> be about 24 GB (allowing for some additional memory for other
>> applications), MaxClients should definitly not be higher than about 400.
>>
>> OK
>>
>>>> How many concurrent users do you expect to use Horde?
>>>
>>> I don't know, how to get concurrent users.  But, as soon as, office
>>> hours start, at least 500 to 600 users will login.
>>
>> That should be manageable with MaxClients equal to 400 (and even quite a
>> bit lower too), provided KeepAliveTimeout is set to a small enough
>> number (not more than the default of 5 seconds, 2 seconds is better on a
>> busy server).
>>
>> In our config of RHEL, default is 15 seconds.  I am changing it to 5
>> seconds as suggested.
>>
>> What you should also check, is if under load the database (or IMAP)
>> performance is not the limiting factor. If the database (or IMAP) is
>> slow, the requests to Horde will take longer to complete and hence, the
>> number of httpd processes will increase. There is nothing Apache or
>> Horde can do about that.
>>
>> OK.
>>
>> --
>> Horde mailing list
>> Frequently Asked Questions: http://horde.org/faq/To unsubscribe, mail:
>> horde-unsubscribe at lists.horde.org
>
> ----- End message from Arjen de Korte <arjen+horde at de-korte.org> -----
>
> Thank you for sharing your valuable guidance.  I Will keep you and list
> updated.
> --
>          Regards
>           Anant
>
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----- End message from ANANT S ATHAVALE <asa at isac.gov.in> -----

Dear List,

Thank you for your valuable suggestions.  Today was a working day and
Horde performed without any issues.  Thanks again for your super support.

I had the following changes done in my setup.

1. APC apc_shm_size  256 MB.  At some time it had reached 150 MB.
2. apache httpd KeepAliveTimeout.  Reduced KeepAliveTimeout from 15
(default) to 5.
3. apache httpd MaxCllients to 400.As

But, I continued to use 'cache' => 'cache' for backends.local.php of IMP. 
Changing it to sql was a problem.  It may be related to my version of
Mysql (RHEL provided).  I will investigate this later.

But, to conclude, the day was problem free and thanks to all those who
guided me to resolve the issues.  As suggested, I had disabled debugging
also.  I was also monitoring APC usage.  It had peaked to 150 MB+.

Thanks again. 
-- 
           Regards
            Anant
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