Solved High CPU usage on J2.5 site

So here's my current extension list:

-Joostrap template (just minifying it now)
-Advanced Module Mgr
-Xtplorer
-Kunena

I've got caching on and Robots.txt is blocking all bots.

Latest CPU stats:

Jun 16 2012: (final stats)********** All extensions still running
joomla.org.au 4.82 1.22 0.0
Top Process %CPU 149 /usr/bin/php /index.php
Top Process %CPU 126 /usr/bin/php /index.php
Top Process %CPU 124 /usr/bin/php /index.php

Jun 17 2012 (partial stats, 06 hours):********** All extensions turned off, including Kunena
joomla.org.au 0.42 1.03 0.0
Top Process %CPU 27.0 [php]
Top Process %CPU 0.3 httpd [joomla.org.au] [/administrator/templates/bluestork/images/menu/icon-16-mess]
Top Process %CPU 0.1 httpd [joomla.org.au] [/templates/system/css/error.css]

Jun 17 2012 (full day): ********** Kunena turned back on part way thru day
joomla.org.au 1.49 1.00 0.0
Top Process %CPU 93.0 /usr/bin/php /index.php
Top Process %CPU 56.5 /usr/bin/php /index.php
Top Process %CPU 55.0 [php]

Jun 18 2012 (partial stats, 03 hours into the day): ***** Kunena back on
joomla.org.au 1.67 1.27 0.0
Top Process %CPU 69.0 [php]
Top Process %CPU 0.3 httpd [joomla.org.au] [/components/com_kunena/template/default/images/icons/stats.]
Top Process %CPU 0.2 httpd [joomla.org.au] [/media/kunena/avatars/resized/size36/users/avatar63.jpg]

You must remember that if Joomla is turned offline, people just visit one page and go away. If Kunena isn't online, people go to forum and see that it's offline and go away. But if Kunena is online, they probably visit 10-100 pages before leaving your site. And it's the amount of traffic that has the highest impact on your CPU load. So 10 pages vs 1 pages means always more than 10x higher average load.

To me it looks like Kunena isn't the issue. Here's the total resource usage during the last minute or so according to your stats (100% = full load):
All extensions = 482% (bad)
Kunena = 149% (still ok)

Don't look individual process CPU time as they are supposed to be as high as possible to be able to serve pages faster. Look the three numbers above: 1.49 1.00 0.0. Those tell you average CPU load now, during the last few minutes and long average. One CPU = 1.00, except on virtual servers where the number means the time that's allocated to you.

So your other extensions are causing almost 3x load compared to Kunena. It doesn't mean that the extensions are slow, but it points to me that the server resources allocated to your site run out and saturate. The effect is the same as in traffic jam: once the limit is reached everything slows down and take 3-5x more time. If situation doesn't get any better, after a few minutes load gets up to 50-100 and every page load takes something like 30-300 seconds.

Your main issue is that your server just isn't powerful enough to run a busy Joomla site with your current configuration. Part of that can be fixed by optimizing Apache/MySQL configuration and removing all extensions that you really don't need. Also upgrading to Kunena 2.0 should help, as it caches some data and should therefore use less resources.

Hello Matias

Thank you for your detailed explanation. Much appreciated.
I understand what you mean now.
As almost all of our extensions are still turned off, and I dont have access to tweak Apache/MySQL, what I draw from this is that we've outgrown our hosting and should move on up to something beefier.

Thanks again
Dex

I see that Dex2's website has become more "serviceable" recently but, considering the kind of load that the site is taking, I am disturbed by processing that yield Kunena page loads of 0.8 seconds on a "grunty" hosted platform. I have offered Dex2 several opportunities to discuss the Kunena aspects of the website in question; I have sent private messages to Dex2 with my telephone contact information and I have posted similarly on the discussion forum at Dex2's website but, unless there is a willingness to pursue this matter further, we may have to consider this a closed case.

Cant currenty measure CPU load, but page loads are now down from 0.8-1.0 to 0.18-0.5 as I have upgraded to Kunena 2.0. A very timely release

Thanks to everyone who has worked so hard to get this new release out. You rock!

And thanks to Sozzled and all of you who have helped with ideas.

cheers
Dex

Oh .. great! Pleased to hear that you have upgraded. Please also apply important patch as described >>> here <<<.

Do this before a new users (who has not yet attached something to their post) attaches something or you will get HTTP 500 errors and the site will be locked out (backed, too). This is an important fix (properly corrected in K 2.0.1 to be released shortly) and necessary for all K 2.0.0 sites running on J! 2.5.x.

Do it now, please.

Nice to hear that upgrade to Kunena 2.0 helped. I did know that our optimizations in K2.0 will make large sites much faster, but it came by surprise on how much faster a small site can be in shared hosting.

I thought that most of the optimizations have little or no impact if there are only thousands of posts, but I had no idea on how wrong I was! Maybe shared hosting environments have some limitations that are unique to them and our optimizations work also in those environments.

Nice! That only will make K2.0.1 the best release ever.