One mistake that bitten me a couple of times is not to reseed after fork(). AFAIR Perl calls srand automatically on fork, and I've been surprised that ruby at c

One mistake that bitten me a couple of times is not to reseed after fork(). AFAIR Perl calls srand automatically on fork, and I've been surprised that ruby at circa version 1.8 - didn't, which gave me quite some interesting behavior on production. I'm sure some other runtimes don't do it, too.