Other major inconveniences I've run into: Collecting metrics require using an external collector process (statsd) rather than just an in-proc lib (e.g., codaha

Other major inconveniences I've run into: Collecting metrics require using an external collector process (statsd) rather than just an in-proc lib (e.g., codahale metrics on the JVM). Issues generating random numbers - I ran 8M simulations on 8 cores, but because the random seed was forked, I actually only ran 1M simulations 8 times. (Easy enough to fix, but annoying.) Deduplication is really handy in reducing memory usage - why would you want the same (immutable) object duplicated N times? And of course various issues with resources - you need to be careful only to connect to the DB/etc after forking otherwise stuff gets weird. And of course, this means that instead of sharing a single connection pool, you've now got one DB connection per proc, which may or may not be a big waste of resources.