[Debug]Apache on Mac OS X couldn't grab the accept mutex

I just ran into a problem where Apache wouldn't start on my Mac OS X laptop (Leopard 10.5.8 although it shouldn't really be relevant as it was working just fine for weeks with that OS version). The following was in the error log:

[Mon Aug 31 12:20:15 2009] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Mon Aug 31 12:20:15 2009] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Mon Aug 31 12:20:15 2009] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Mon Aug 31 12:20:15 2009] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Mon Aug 31 12:20:15 2009] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Mon Aug 31 12:20:16 2009] [alert] Child 1294 returned a Fatal error... Apache is exiting!


The solution is to find the AcceptMutex line in your httpd.conf (add one if you don't have it already) and change it to

AcceptMutex flock

Rock on.