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My problems with my site continue. I got timeout errors initially. The server ground to a halt, very high memory use by Apache. Site came back with no pages. I found that deleting the most recent post in wp_posts brought the site back up. Sysadmin pointed out high cpu use by apache but this may be a red herring, the memory not cpu is an issue. It seems that when user uploads a file, the memory used by Apache goes through the roof eventually bringing the site down. The files aren't that large so it's not php upload_max_filesize causing it. I suspect the problem is being caused by a plug-in. the plug-ins I have are:

  • contact form 7
  • contact form to db extension
  • enable media replace
  • health check
  • Relevannsi
  • Simple expires
  • User access manager
  • Category posts
  • breadcrumb trail
  • configure SMTP

Does anyone know of any issues with any of these, or does an issue with plug-ins sound like a likely cause? I get Fatal error: out of memory error now. User told me it went when he tried to upload file.

share|improve this question
If you're on WP 3.3+ you can try this plugin which analyzes the performance of plugins: wordpress.org/extend/plugins/p3-profiler Might want to try on a local copy of the site first though as running the plugin can cause memory issues if you're already overloaded...' – Michelle Jan 18 '12 at 17:09
You have a ZERO PERCENT ACCEPT RATE: 7 questions asked, and 0 accepted answers. – Chip Bennett Jan 18 '12 at 17:22
when you're uploading images, the php GD library can require large amounts of memory to produce the alternate image sizes, it all has to fit in RAM. a sub 1mb image can consume many times that size during processing. adding all your other memory needs on top of that can push it over the edge. – Milo Jan 18 '12 at 17:22
Also: this appears to be a duplicate. – Chip Bennett Jan 18 '12 at 17:32
Thanks Chip. I'll deal with that. I don't think its a duplicate though. – Tony B Jan 18 '12 at 18:31
up vote 1 down vote accepted

To diagnose a load-intensive (either CPU cycles or memory) Plugin, start by deactivating all Plugins. Ensure that, with no Plugins active, you do not observe the same issues.

If you observe the same issues with all Plugins deactivated, then the problem is somewhere else, either with your Theme, your database, or your server configuration.

If you don't observe the same issues with all Plugins deactivated, then activate one Plugin at a time, individually, to determine if one is causing the problem. It is possible that a single Plugin, on its own, is causing the problem. If so, this step will help identify that Plugin.

More likely, however, is that the problem is a cumulative effect, or caused by an interaction of multiple Plugins. In that case, you will have to active Plugins cumulatively, until you identify the cause of the problem.

Note, I would recommend the Server Buddy Plugin for monitoring resource usage during this testing.

share|improve this answer
Thanks Chip, I was thinking along these lines but wasn't aware of this plug-in. Much appreciated. – Tony B Jan 19 '12 at 20:20

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