Intermittent slow page generation

[clefty]

Hi,

I'm having a really strange issue with my CMSMS sites.

Background:

VPS with 512Mb dedicated RAM, 1Gb burstable which is running 6 low traffic (and non-database intensive sites)

Server: Apache 2.28, PHP 5.2.6, Zend Optimizer, eAccelerator, MySQL 5.0.51a.

The server is in no way overloaded, load averages around 0.3. Non CMSMS sites run without problems or latency. (Hosting company is Clook who have excellent network and reputation. The VPS node I'm on is running latest Viruozzo and currently has no issues performance, stability-wise according to Clook)

PHP memory limit 32MB

MySQL query cache enabled and my.cnf parameters optimised for the Virtuozzo RAM settings.

MySQL slow query logging is enabled and showing nothing.

Issue:

First call to CMSMS page can take 45 - 60 seconds. A page refresh returns a generation time of 0.1 - 0.3 seconds as does navigating around the site. Leave the site for 30 minutes then return - back to ridiculous generation times for the first page load, then subsequent pages fine again.

I have spent several months following various threads on the forum regarding speeding up the sites:

1. Uninstalled and removed all unused modules
2. Ensured caching is enabled on all pages
3. Installed {static_stylesheet} mod
4. Using file based menu templates

Pages generate average of 25 SQL queries.

CMSMS versions: 1.4.1. No additonal modules installed.

This post is really targeted at the network, LAMP gurus. I can't see this being a CMSMS code issue. Crappy hosting would surely give consistently slow parsing times. The post first page generation times of 0.1s appear from the forums to be in the acceptable to good range.

Does anyone have any idea which component of the hosting setup could be causing this weird behaviour?

Any help greatly appreciated. I love CMSMS and can't bring myself to use anything else  Been over the others and have found my home with CMSMS.

[calguy1000]

Well if you're on a VPS, the first thing I would do is install eaccelerator.

That aside, widely inconsistent results lead me to think that there is some kind of wierd stuff going on with your host.

I would start by checking to make sure that your files in tmp/cache and tmp/templates_c aren't for some stupid reason getting nuked on a
regular basis.  Maybe some funky cron job or something.

Other than that, I'd monitor the server logs (dmesg, etc)... and monitor the server load (uptime), and memory (free) and see if you can find something.

[clefty]

Thanks for the quick reply Robert.

eAccelerator got compiled the day I got the VPS (you probably missed this bit in my waffle!)
I'll probably turn on eaccelerator logging for a few days to see if anything shows up here but its logs get big very fast ...

I'm pleased you're thinking on the same lines as me - hosting not code. It's so frustrating trying to nail this down.

My first thought was that the cache/templates were being deleted / corrupted but they're all present and with the correct permissions and modified dates.

I've also been considering:

1. Problem with BIND and initial DNS lookup but why would non-cmsms sites lookup normally? (rhetorical questions ... just thinking out loud)

2. Problem with MySQL query cache lifetime? Is there a bug in my MySQL engine that's clearing the query cache after a short interval causing the delay whilst the initial CMSMS queries get recached?

I'll start monitoring the usual suspects in dmesg, top, ps as you suggest.

Many thanks again,

Chris

[moonoo]

I am experiencing similar issues on first load of site on most installs using CMSMS.. anytime the site is accessed first I am getting 16s before site loads.. after this everything loads fine.. upped memory limit and but made no difference. looking at chrome developer panel indicated the generation of the index document itself is what takes the longest..

Any clues here would be greatly appreciated.. Same sever, same site using symphony-cms does not suffer the same latency issues.

[reneh]

I'm not an expert in any anyway...  to tell that first.


But first load are db queries  and repeated loads are more cache.
So I would concentrate to look at the query times to db here...


The next note I have is UPGRADE! 
CMSMS core 1.4.1 is  "Released On: 2008-08-09 15:03"
Only supported version today are 1.7. and 1.7.1. You should go minimum to 1.6.7 since that is the latest security release.
AND 1.4-versions (and some before) was slow as far I remember...