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On a ubuntu server, I run a LAMP environment with APC, and fast-cgi as php mod, to host 2 wordpress sites, and both sites have Wordpress Total Cache (W3TC) plugin configured.

The server's specs are: 2gb ram and 1 cpu (cpu MHz: 2100.076, cache size: 2048 KB).

One of the sites, generates a pretty heavy load on the server and oftenly the server stops to respond because of the high load.

  • I've deactivated unused Apache modules
  • I have set that all the caching from W3TC to be done in memory with APC
  • I did some apache tweaking

But none of that actually helps me with the brutal CPU usage, from php-cgi.

While I implement varnish and try to have a replica on another server I have so I can also do some load balancing, I'm wondering how can I set some kind of load limit on php-cgi or apache its self, and show a custom message like: Sorry, the server is under heavy load, please try again later

Have to mention that I also use, cloudflare.

Any other tips, are very welcome as well.

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I don't know the answer, but I always assumed this was done by the load balancing server. Is there no way to setup cloudflare to display a specific message if the server doesn't respond? – user606723 Apr 4 '13 at 13:11
I had same problem when i used CloudFlare. After i used they DNS, 8 cores system went to 50% usage. The most processes was Apache. Also MySLQ was 100-120-150% all the time. Few days after i stopped to use it and cpu usage is back to 6-10%, also MySQL usage is back to 10-30%. All the time same number of users was online (its game server). I am using CentOS 5, 8 cores, 16gb of RAM. – EmptySD May 7 '13 at 7:55

What are the typical request rates for PHP generated and static content? Have you checked the hit rate in APC for caching and for opcode? What version of PHP?

show a custom message

The sensible place to do this would be on a reverse proxy - but you say you've not go this in place yet. Another approach would be to run a minimal webserver and load balancer on the current box (in addition to the main content) and redirect that way - but that's even more work than getting Varnish set up.

Similarly wrapping the front end in a proxy script would have the desired effect - but again, the effort is more than implementing Varnish.

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PHP 5.3.20-1 with suhosin v0.9.33, but honestly, I have no idea how to find out the request rates for PHP. APC Hits: 69735 (99.1%), Misses: 635 (0.9%) – w0rldart Apr 4 '13 at 19:51
And the amount of work is not an issue, I like work, especially when it will improve something – w0rldart Apr 4 '13 at 19:52
Any update based on the comments? :) – w0rldart Apr 9 '13 at 11:32

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