[tychver]

Forking 10 processes does not use 10x the memory of a single process starting 10 threads. It's actually almost identical. Both are implemented by the kernel using clone(). Many older tools written in "fast" languages like PostgreSQL and Apache also use forking.

[hasenj]

We're not talking about forking here. Python/Ruby apps are actually spawned as several separate processes.

[tychver]

Not for almost a decade. Ruby web servers and job processing frameworks have used forking out of the box since the release of Phusion Passanger 2 in 2008 and Resque in 2009.