[horde] Too many httpd processes and no response

[Michael M Slusarz]

Quoting Arjen de Korte <arjen+horde at de-korte.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?
>
>> 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.
>
>> 3. Using PHP 5.3.3-27 as provided with RHEL

As has been mentioned multiple times on this list: Horde /can/ run on  
PHP 5.3.3.  But it makes absolutely no sense to do so, due to both  
security, bug, and performance issues.

A large client (think millions of users) recently informed me that the  
simple process of upgrading from PHP 5.3 caused a drastic improvement  
in performance.

>> 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?
>
>> 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.

This is probably your issue.  Look at your I/O numbers (e.g. via vmstat).

michael

___________________________________
Michael Slusarz [slusarz at horde.org]