> Odd thing #1: As it gets into evening time, load on the machine drops off
> and there are fewer httpd children running, but I am not seeing free
> memory return to that 1.3GB level. At most it comes back up to 400MB or
> so. I don't think the httpd children are hanging on to memory, because
> they cycle through pretty quickly - MaxRequestsPerChild is set to 512 and
> none of the processes are ever more than a couple minutes old when I look
> in. Is there any reason to think the parent httpd process would hang on
> to anything?
I have noticed that over time the new processes will spawn with less memory
shared. I'm not sure exactly why this is, but it does seem to happen. A
nightly complete restart of the server will reset things, but you may not
have that option.
> Odd thing #2: (This part seems most bizarre to me.) At 5:15 AM, we run a
> Perl script that finds and deletes Apache::Session::File session and lock
> files that are older than 28 days. Usually there are about 50,000 old
> files that get deleted out of about 2,300,000 total. Almost immediately,
> free memory on the machine jumps back up to 1.3GB. What's up with that?
Sounds like you're counting the buffers and cache in your "used" memory.
Depending on what OS you're on, you may want to look at a tool other than
top. The memory used for buffers and cache will be available to
applications if they need it.
- Perrin
