Re: [PHP] Command-line PHP script CPU usage goes sky-high, stays there--why?
- From: trogers@xxxxxxxxxx (Tom Rogers)
- Date: Tue, 11 Dec 2007 09:42:50 +1000
Hi,
Tuesday, December 11, 2007, 6:42:18 AM, you wrote:
RF> Hello,
RF> I have a command-line PHP script--called Listener--that is designed
RF> to run indefinitely with a predictable CPU usage and memory
RF> footprint. In a nutshell, it's a multi-client socket server that
RF> waits for incoming connections, processes incoming data, stores
RF> results in a MySQL database, and basically gets on with its life. And
RF> it works. No errors or serious problems to speak of. And I've been
RF> running it for a couple years on an Xserve dual-G5 2GHz w/ OS X
RF> Server 10.4.11). Six months ago, the program would run for days, even
RF> a couple weeks, without a hitch. The only reason I would stop the
RF> script is for some other purpose, like a software update.
RF> However, the number of socket clients connecting in the past 3-4
RF> months has steadily increased, and this seems to have exposed (if not
RF> created) a strange performance "issue" with PHP 5.2.4, MySQL 5.0.45
RF> and/or Mac OS X Server 10.4.11. (I say "and/or" because I am unsure
RF> where the problem's cause really lies.) Basically, after the script
RF> has been running for a day or so (processing essentially the amount
RF> data that used to take two weeks), the CPU usage of the machine goes
RF> from 30% (normal) to 80-90%. This appears to be irrespective of the
RF> number of clients connected to the server at the time, but rather the
RF> amount of time the script has been running (and therefore cumulative
RF> cycles it's operated, data processed, MySQL queries executed, etc.).
RF> And the CPU usage stays high, even when the actual load (number of
RF> clients) decreases. At this time, if I run top, I get the following
RF> info:
RF> 22512 mysqld 91.6% 8:22:12 31 106 125 305M+ 3.20M
RF> 260M 475M
RF> 17104 php 7.2% 81:14.01 1 15 145 5.08M 7.80M
RF> 10.9M- 87.5M
RF> 22537 Terminal 6.6% 2:59:59 22 176 240 12.3M 21.2M
RF> 18.3M- 236M
RF> [...]
RF> At first I thought, okay, it's MySQL's fault. Maybe a lot of slow-
RF> running queries. But the slow query log is pretty clean. So maybe
RF> it's a combination of Mac OS X and MySQL and PHP? I Googled for a
RF> similar problem, and finally ran across this article:
RF> http://www.shawnhogan.com/2005/10/mysql-problems-on-mac-os-x-server.html
RF> ...where the author describes a very similar CPU usage pattern. I
RF> tried his suggested fixes and they seemed to have helped a little (or
RF> maybe it's my wishful thinking--hard to tell), since the high CPU
RF> load issue doesn't appear to happen as soon... But it still happens.
RF> Anyway, I'm really stumped as to what to do next, where to look, etc.
RF> If I stop the script, and restart it (but not the MySQL itself), CPU
RF> usage goes back to normal--for about a day or two.
RF> The only thing I thought might be connected is how many short-lived
RF> PHP child processes Listener creates--around 20-30,000 per day.
RF> Sounds higher, but on average it's just one every 2-3 seconds.
RF> Anyway, although the number of child processes isn't concurrent,
RF> would there be a problem with the number of historical child
RF> processes in view of ulimits or kern.maxfilesperproc?
RF> Anyway suggestions, tips, or links are much appreciated. Thanks.
RF> ...Rene
Put a usleep(1000) in the listen while() loop and give the cpu a
break.
--
regards,
Tom
.
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