OSX has a ridiculously low limit on the maximum number of open files. If you use OSX to develop Node applications -- or even if you just use Node tools like grunt or gulp -- you've no doubt run into this issue. To address this, I have this line in my $HOME/.bash_profile: ulimit -n 1000000 unlimited And a corresponding entry in /etc/launchd.conf: limit maxfiles 1000000 That solved the problem until