I am running Mac OS X 10.9.4, including the builtin apache2 webserver with PHP 5.5.14 from brew (packages: php55, php55-intl, php55-pdo-pgsql, php55-xdebug).

When running this setup it works quite well. However, after some time, I will run on 403 errors for every request. I have looked up the apache error log, and found something like the following:

[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP Warning:  require_once(/Users/daniel/Development/massiveart/sulu-complete/app/bootstrap.php.cache): failed to open stream: Too many open files in /Users/daniel/Development/massiveart/sulu-complete/web/website.php on line 10, referer: http://sulu.lo/de
[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP Stack trace:, referer: http://sulu.lo/de
[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP   1. {main}() /Users/daniel/Development/massiveart/sulu-complete/web/website.php:0, referer: http://sulu.lo/de
[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP Fatal error:  require_once(): Failed opening required '/Users/daniel/Development/massiveart/sulu-complete/web/../app/bootstrap.php.cache' (include_path='.:/usr/local/Cellar/php55/5.5.14/lib/php') in /Users/daniel/Development/massiveart/sulu-complete/web/website.php on line 10, referer: http://sulu.lo/de
[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP Stack trace:, referer: http://sulu.lo/de
[Fri Jul 25 05:28:18 2014] [error] [client 127.0.0.1] PHP   1. {main}() /Users/daniel/Development/massiveart/sulu-complete/web/website.php:0, referer: http://sulu.lo/de
[Fri Jul 25 05:28:40 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de
[Fri Jul 25 05:28:41 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de
[Fri Jul 25 05:28:41 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de
[Fri Jul 25 05:28:41 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de
[Fri Jul 25 05:28:45 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de
[Fri Jul 25 05:28:45 2014] [crit] [client 127.0.0.1] (24)Too many open files: /Users/daniel/Development/massiveart/sulu-complete/web/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable, referer: http://sulu.lo/de

It looks to me like the file cannot be read anymore, and it returns the 403 somehow. I already found out about certain limits, but launchctl returns I have an unlimited hard limit on open files:

 ~ $ launchctl limit
    cpu         unlimited      unlimited
    filesize    unlimited      unlimited
    data        unlimited      unlimited
    stack       8388608        67104768
    core        0              unlimited
    rss         unlimited      unlimited
    memlock     unlimited      unlimited
    maxproc     709            1064
    maxfiles    256            unlimited

I have also already tried to set the maxfiles to 4096 with the command launchctl limit maxfiles 4096 16384, but the issue still returns after some time. Any idea what else I can check?

UPDATE:
When running the lsof -c httpd command as suggested by Gordon Davisson, I can see that there are loads of entries like the following:

httpd   1361 _www   15u    IPv4 0xb306b48659f63853       0t0     TCP localhost:50603->localhost:cslistener (CLOSED)

I can say that the application I use is using websockets, and is also using a fallback when websockets are not available or the counterpart is not running on the server. What confuses me is the (CLOSED)-part, why is it still listed?

UPDATE:
After some time I looked up the cslistener port, which actually is 9000, which again is which port xdebug is listening for remote debugging. So I guess I have got some wrong configuration there, or it is a bug in xdebug (I am using XDebug 2.2.5, installed by brew)