Question How to improve performance?

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No problem -- I was just worried about potential problems with upgrading from 5.2.17 to 5.3.8.

I gave it a whirl last night using easyapache, and it appeared to work fine.

Sadly.. when I went to the Joomla backend and to the Global Configuration tab, I received an "Out of Memory" error. I reverted back to 5.2.16 because it was late at night and the site needed to be operational for the school day.

I may give it a shot again later tonight -- but what would change in going from 5.2.17 to 5.3.8 that would cause the Global Configuration tab of Joomla to error out of memory? Other sections of the backend were working just fine. I had taken the site offline before the upgrade, so I was unable to check if Kunena was functioning correctly.


I did, however, enable mysqli and I'm assuming that I need to make the change from mysql to mysqli in the Joomla backend in order to take advantage of it, correct?


What role does xcache play in handling the queries used by Kunena?

XCache is a fast, stable PHP opcode cacher
This will speed up site for users

php update recommended but not required

Test load can be loadimpact.com

Alright, I've enabled everything including xcache so far, including upgrading to php 5.3.8 (which introduced a single error with loading the Joomla Global Configuration page (everything else works just peachy) -

Fatal error: Out of memory (allocated 34078720) (tried to allocate 2201437 bytes) in /xxxx/libraries/joomla/environment/response.php on line 149

So I'm working to resolve that.

Load times for Category pages and discussion topics have decreased by about 25%, but we're still talking load times of 5-7 seconds to load a topic.

The handler_read_rnd and handler_read_rnd_next are still enormous, which I'm thinking is what is causing these massive slowdowns.

If I have a lot of user groups, with access to specific categories (to handle classes and groups in those classes), is there something in the Kunena queries that wouldn't be able to handle reading permissions for categories / topic posts?

I believe that your issues comes from 1GB of memory -- every user in Apache takes 32MB of memory, meaning that your server runs out of memory if there are over 5-15 users (depending how much memory other processes take) loading the page at the same time. After that it starts using swap files, which almost always explain 30-180 second delays between page loads.

You should run "top" to see what happens in your server during peak time. Look especially 3 things:

1) load average: 1.0 means 100% usage in one processor. Usually it gets very high soon after that...
2) Mem/Swap: Your server should never run out of memory and start filling swap. It just kills your server..
3) Process list: look which one is in top: apache or mysqld (count %CPU together for Apache)

Here are the scenarios:

1) Memory runs out, swap grows fast (and site gets slow)

There are only 2 options: add more memory or limit how many processes Apache can run. First option is optimal in this case, but second should make page loads one magnitude faster (30 -> 3 seconds).

2) Apache processes take most CPU time

In this case installing xcache, apc, eaccelerator or similar usually helps, but even then you can only serve at most 2 times more users than without opcode caching. Usually one processor like yours can serve 2-3 requests per second (more with opcode caching), so if you have more there's no other way than having more powerful server. Just be warned that opcode cache may cause other issues (random white pages etc), so if you get reports from those, you know what to blame for..

3) Mysql takes most CPU time

InnoDB can be configured to load tables into memory. In that case it runs fast -- but needs about the amount of memory that your database takes.

Fatal error: Out of memory issue: php.ini has memory_limit = 32M. Make that larger or make your pages simpler by removing all modules and plugins that you really don't need. Also disabling JomSocial/CB integration helps to save memory.

Matias, thank you very much for the detailed explanation -- extremely helpful as we plan going forward.

Do you have any idea what would be causing the high number of queries that don't use an index? Even on a completely empty server, bringing up the list of categories is sluggish - and these are consolidated categories, not the full index. I'd imagine that Kunena just isn't designed to 308+ categories with individual permissions?