Enabling SMP Support for Erlang on Mac OS X

If you are working with Erlang on Mac OS X and have installed it via Mac Ports, then you might not be running the SMP enabled erlang.

To check, start erlang as

erlang -smp

If you get:

Argument '-smp' not supported.

Then your erlang was not compiled with SMP. All you'll need to do is:

sudo port uninstall erlang
sudo port install erlang +smp

Then when you run erlang -smp, you'll be dropped right into the erlang shell. When you run anything with multiple processes, you'll see both of your CPU cores active.