Apache/PHP memory usage

Question

I have a test WordPress blog on my server. Before loading a WordPress page in my broswer, my server's used memory is about 190MB. But after loading a few pages from my test blog, my server's used memory jumps to around 420MB.

I don't mind WordPress using so much memory, but what I'm struggling to understand is why does the memory never release from the system until it's rebooted?

The server doesn't seem to be slowing down but I'm concerned that it'll eventually run out of memory.

Am I paranoid or is it a genuine concern?

test it. keep making requests until it fails

gwillie
– gwillie

2013-09-29 05:14:00 +00:00
Commented Sep 29, 2013 at 5:14 — gwillie
– gwillie, Commented Sep 29, 2013 at 5:14

Dave Ross · Accepted Answer · 2013-09-30 03:35:10Z

1

Without getting too technical, allocating & releasing memory are expensive operations in terms of processing resources. So long-running processes like PHP will hang onto their RAM as long as possible and re-use it, rather than asking the operating system for more memory all the time.

Apache has a setting for how many requests a particular PHP process can handle before it's killed, releasing its memory, and re-started. Chances are you aren't coming anywhere near this number of requests on your test blog.

answered Sep 30, 2013 at 3:35

Dave Ross

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