[horde] Too many httpd processes and no response

Tue Jan 14 09:40:47 UTC 2014

  ----- 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
>
> 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.
>
> 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.
>
>>>> I am unable to diagonise this right now.
>>>>
>>>> 1. I have installed HGWE on RHEL 6.4
>>>> 2. Using APC Cache as provided with RHEL
>>>
>>> Is there enough memory available for APC? Look at the apc.php status
>>> page to see if there is sufficient memory available, especially if
>>> you're using it as a caching backend.
>>
>> This, I have started monitoring now.  Being a holiday today, it has
only
>> used 56.2 MB.  I had restarted httpd yesterday evening.  Right now, I
>> have set it to 256 MB.  System has 32 GB RAM.
>
> Monitor that value under use and make sure it is never for more that
> about 75% full.
>
> OK.
>
>>>> 3. Using PHP 5.3.3-27 as provided with RHEL
>>>> 4. Using SquirrelMail IMAP proxy latest stable version, compiled on
the
>>>> same server.
>>>> 5. Using Cyrus-IMAP server on a remote server and following string
>>>> logged
>>>> in Horde-IMAP debug log
>>>>
>>>> S: * OK [CAPABILITY IMAP4rev1 LITERAL+ ID ENABLE  XIMAPPROXY]
>>>> newisacmail.isac.dos.gov.in Cyrus IMAP v2.4.17-Invoca-RPM-2.4.17-6.el6
>>>> server ready
>>>
>>> Have you enabled IMAP caching in imp/config/backends.local.php?
>>
>> following is the conf.php for Horde.
>>
>> $conf['session']['cache_limiter'] = 'nocache';
>> $conf['share']['cache'] = false;
>> $conf['cache']['default_lifetime'] = 86400;
>> $conf['cache']['driver'] = 'Apc';
>> $conf['cache']['use_memorycache'] = 'Apc';
>
> This is redundant. You're already using a memory caching backend, so
> 'use_memorycache' has no effect.
>
>> $conf['cachecssparams']['driver'] = 'filesystem';
>> $conf['cachecssparams']['lifetime'] = 86400;
>> $conf['cachecss'] = true;
>> $conf['cachejsparams']['driver'] = 'filesystem';
>> $conf['cachejsparams']['compress'] = 'php';
>> $conf['cachejsparams']['lifetime'] = 604800;
>> $conf['cachejs'] = true;
>> $conf['cachethemesparams']['check'] = 'appversion';
>> $conf['cachethemesparams']['lifetime'] = 604800;
>> $conf['cachethemes'] = true;
>>
>> and backendslocal.php for IMP it is:
>>
>> 'cache' => 'cache',
>
> This value is not recommended. From the comments in
> 'imp/config/backends.php':
>
> *     - 'cache': Caching is enabled using the Horde cache (configured
in
> *           horde/config/conf.xml). It is recommended to use either
> 'nosql'
> *           or 'sql' instead, as these backends have much better
> performance.
>
>> Do I need to change this to NoSQL?
>
> If you already have a NoSQL server available, yes. If you don't, a SQL
> server will work just fine. Given the amount of data to store, you'll
> not want 'cache' here, since potentially there will be way more data
> than the memory caching backend you have configured can store.
>
> I am switching over to SQL.
>
>>>> I am unable to debug why httpd suddenly starts too many processes.  I
>>>> have
>>>>
>>>> already enabled DEBUG log in Horde conf.php
>>>
>>> Definitly don't do this. Your investigating a performance problem here.
>>> Logging at level DEBUG will generate tons of information and on a busy
>>> server this will be enough to bring it to its knees.
>>
>> Today, being holiday, I will continue with DEBUG and disable in the
>> evening.
>
> Again, DON'T DO THIS! NEVER, EVER enable DEBUG on a production system!
> You'll get WAY too much logging to be useful on a production system.
> Typically, DEBUG is used on a system with a single (test)user to
> diagnose what is going on if a function of Horde doesn't work as desired.
>
> I will disable DEBUG, as you suggest. 
>
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----- End message from Arjen de Korte <arjen+horde at de-korte.org> -----

Thank you.  I will keep updating.
-- 
           Regards
            Anant
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