I'm having a problem. My AIX Unix server keeps crashing because it's memory keeps swapping to max. When I do a "ps aux" command, there are dozens and dozens of Apache group processes running. Most of them run for hours! How come they are not ending automatically? I end up killing those processes manually until my server speed comes back. I know this is a long shot, but what could be the problem?
The Apache does grab data from MySQL via PHP (heavy traffic shopping cart). I've heard complaints that one of my formmails on the site gives an Error 500 (script crash). Shouldn't Apache know to automatically end those crashed sessions, or could these be the culprit? I've been going nuts trying to track down this problem. Pls help!
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Your long term solution is to probably buy more memory, but in the short term you should probably increase the size of your paging space so that your server does not run out of memory. You can change it with the 'chps' command (or make a new paging volume with mkps) Both operations are also available in 'smitty' under System Storage Management (Physical & Logical Storage)->Logical Volume Manager->Paging Space as well.
Thanks for the help. What boggles me is that these Apache processes remain in the processor list for hours. Shouldn't Apache end these process if they are finished. No process should take more than a minute. Even if the visitor looks around my site then leaves his computer idle, there should be no processor running since it idle on a static page (after it has been generated). Is this right?
These processes don't serve only one request for their lifetime. They are server processes that are meant to be kept running indefinitely. The reason being that if you had to create a new process every time a user connected to your website, this would result in a tremendous amount more overhead than if not...
With that said, if you have a memory leak in something running in these processes, the leak will eventually consume all of your memory. In addition, if you have periods of high load on your server, you will have a lot of processes running at any given time that you don't need. Have you confirmed that you don't have a memory leak somewhere?
There is a setting that you can use to occasionally refresh/restart these processes called 'MaxChildRequests'. It is set to 0 by default, which means that they are never restarted. The value for this setting indicates how many requests will be served by the child before it is recycled. I would play around with this number - it should be set according to how busy your server is. IE: You're looking for a balance between restarting before the problem arises and not constantly restarting. (Perhaps try a setting of 1000 to start)
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by: gripePosted on 2007-01-06 at 08:28:47ID: 18258451
If you have a lot of apache processes running you probably need them. Apache will start children to service requests up to the maximum defined in your configuration. You've indicated that you have a heavy traffic site so this seems normal. When you're killing processes you are very likely killing someone's connection to your webserver. You should adjust the maximum number of clients in your apache configuration file. (But again, if you have too many apache servers running, you likely need them and adjusting these values will probably reduce the amount of clients your server can handle at any given time) You can find the details around these configuration directives here:
http://httpd.apache.org/do
The cause of 500 errors will usually be found in your error logs and it's unlikely that the fact that you have a lot of apache children and you're getting 500 errors are related.