Intermittent "too many open files" when including/requiring PHP scripts - php

Question

On my development box (thank goodness it's not happening in production—that I know of—yet), as I'm working on a PHP site, I get this occasional error:
Warning:
require_once(filename.php): failed
to open stream: Too many open files in
path/functions.php on line 502
Fatal error: require_once(): Failed opening required 'filename.php'
(include_path='/my/include/path') in
path/functions.php on line 502
Line 502 of functions.php is my "autoload" function which automatically requires PHP files containing classes I use:
function autoload($className)
{
require_once $className . ".php"; // <-- Line 502
}
By an "occasional" error, I mean that it'll work fine for about a day of development, then when I first see this, I can refresh the page and it'll be okay again, then refreshing gives me the same error. This happens just a few times before it starts to show it every time. And sometimes the name of the file it's requiring (I have a script split out into several PHP files) is different... it's not always the first or last or middle files that it bombs on.
Restarting php-fpm seems to solve the symptoms, but not the problem in the long run.
I'm running PHP 5.5.3 on my Mac (OS X 10.8) with nginx 1.4.2 via php-fpm.
Running lsof | grep php-fpm | wc -l tells me that php-fpm has 824 files open. When I examined the actual output, I saw that, along with some .so and .dylib files, the vast majority of lines were like this:
php-fpm 4093 myuser 69u unix 0x45bc1a64810eb32b 0t0 ->(none)
The segment "69u" and the 0x45bc1a6481... number are different on each row. What could this mean? Is this the problem? (ulimit is "unlimited")
Incidentally (though perhaps un-related), there's also one or two of these:
php-fpm 4093 myuser 8u IPv4 0x45bc1a646b0f97b3 0t0 TCP 192.168.1.2:59611->rest.nexmo.com:https (CLOSE_WAIT)
(I have some pages which use HttpRequest (PECL libraries) to call out to the Nexmo API. Are these not being closed properly or something? How can I crack down on those?)

Answer 1

Try to set php-fpm (they're set to infinite by default) to more appropriate values on your needs.
For example:
emergency_restart_threshold = 10
emergency_restart_interval = 1m
process_control_timeout = 10s
Maybe, set this too if your app works with lots of files:
rlimit_files = 1024