[horde] apache cpu usage?

[avp at rokeyetee.com]

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

> Citeren avp at rokeyetee.com:
>
>> Quoting Michael J Rubinsky <mrubinsk at horde.org>:
>>
>>> Quoting avp at rokeyetee.com:
>>>
>>>> I'm running Horde on a AWS t2.medium instance - HORDE GROUPWARE WEBMAIL
>>>> EDITION 5.2.6
>>>>
>>>> I've got some funny apache behaviour that just doesn't seem right to
>>>> me...
>>>>
>>>> When I run "apache2ctl status", 99% of the time all threads are in the
>>>> "W"
>>>> (Sending Reply) state:
>>>>
>>>>    Current Time: Thursday, 18-Feb-2016 10:02:53 NST
>>>>    Restart Time: Thursday, 18-Feb-2016 09:49:25 NST
>>>>    Parent Server Config. Generation: 1
>>>>    Parent Server MPM Generation: 0
>>>>    Server uptime: 13 minutes 27 seconds
>>>>    Server load: 0.77 0.77 0.85
>>>>    Total accesses: 1382 - Total Traffic: 7.7 MB
>>>>    CPU Usage: u230.64 s11.47 cu0 cs0 - 30% CPU load
>>>>    1.71 requests/sec - 9.8 kB/second - 5.7 kB/request
>>>>    20 requests currently being processed, 8 idle workers
>>>>  
>>>> _WWWWWW_WWWWW__W_WWWWWW__W.K_...........
>>>>
>>>> It seems strange to me that "sending reply" would be the bottleneck?
>>>>
>>>> Also when I run top, I constantly see apache procs jumping to the top
>>>> with
>>>> up to 50% cpu usage.
>>>>
>>>> Most all the connections are ActiveSync.
>>>
>>> When an ActiveSync client is configured for "Push", the connection to
>>> the webserver remains open while it runs the PING command. These
>>> requests last up to the "hearbeat interval" that is negotiated between
>>> the server and client unless there is a change detected, when the PING
>>> requests ends and a new SYNC request is issued. It makes complete sense
>>> that you would see ActiveSync connections remaining open.
>>
>> Thanks for the quick reply.
>>
>> I'm not questioning that the ActiveSync connections remain open - I  
>> get that.  I'm questioning that the connections are in the "Sending  
>> Reply" state?  And that my CPU usage seems too high to me?  I'm  
>> wondering if there is some php being called to generate the reply  
>> that is being sent but it is taking abnormally long/excessive cpu?   
>> Just sort of guessing here...  How might I track down what is using  
>> the cpu or why the connections are in the sending state?
>>
>> Here are my activesync settings:
>>
>> $conf['activesync']['ping']['heartbeatmin'] = 60;
>> $conf['activesync']['ping']['heartbeatmax'] = 2700;
>> $conf['activesync']['ping']['heartbeatdefault'] = 480;
>> $conf['activesync']['ping']['deviceping'] = true;
>> $conf['activesync']['ping']['waitinterval'] = 10;
>>
>> I just changed waitinterval from 5 to 10.
>
> That is still an awfully short interval. It will mean that the PHP  
> process that is kept active for each device that is connected  
> through ActiveSync will poll the users mailbox every 10 seconds.  
> Depending on the number of users you have, this may constitute a  
> fairly significant load. Note that if you have a decent IMAP server  
> such a short interval is a waste of effort anyway, as the IMAP  
> server will notify that things have changed.
>
>> Any suggestions on what these should be?
>
> If you have a significant number of users connected through  
> ActiveSync, increase waitinterval to something like 60 seconds (or  
> more).
>
>> Any other tips/advice to lower CPU usage?
>
> Which IMAP server are you using and how many ActiveSync devices do  
> you have connected?

I'm running Dovecot 2.2.9. Are there any Dovecot settings that are  
recommended?

There are maybe around 30 active ActiveSync connections.

Currently, apache2ctl status reports 1.94 requests/sec - this number  
seems nice and low to me - I don't think I should be killing my cpu?

What are others using for wait interval?

Thanks for the input.

>
>> Thanks again.
>>
>>>
>>>> What are recommended settings for apache when running Horde?
>>>>
>>>> Any other tips/advice to lower CPU usage?  
>>>> Thanks.
>>>>
>>>>  
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>>>
>>> --
>>> mike
>>> The Horde Project
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>>
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