EventMachine

[gchpaco]

This is probably only of interest to perhaps three of you, but what the heck.
I discovered today that EventMachine, a very commonly used Ruby library, has a completely broken popen implementation. Specifically, it doesn't ever call waitpid unless you are

• Running on Linux and have selected the epoll option
• or the process closes all of its input sockets.

In practice this means that if your subprocess spawns a background process and exits, EventMachine will not notify you of that process exiting until the subprocess dies too.
Lost a couple hours to this. It is in no way atypical of either EventMachine or Ruby, sadly.