[the_why_of_y]

Copy-on-write doesn't work the same on every OS... Linux uses over-commit so it's not a big deal, but Solaris (and NT) don't over-commit so you actually need enough VM at the time when you call fork or fork will fail, so you may need to provide a lot of swap space on those systems to successfully call fork in large processes.

[evanj]

Ah thanks, that makes sense. Fun trade-offs: Either run out of memory when you call fork, or fight with the out-of-memory killer at a later time :)