Hello!
I need help:
	Is Ruby multithreading cooperative or preemptive?

I mean: am I forced to abuse of Thread.pass in (every heavy) threads or 
may I just assume the ruby interpreter will commute threads itself?

Another question:
	Is Ruby multithreading blocked by system calls?

Like for example when calling system("command line").

If "no" to any of these questions, can I expect Ruby to work that way 
someday?

Thanks for the help,
Lionel Thiry