Silly question about IORefs and MVars
Sun, 17 Nov 2002 19:33:18 +0100
I have a silly question about IORefs and MVars.
When do we have to use MVars if a var is accessed by multiple threads.
In fact, I wonder why IORefs updates aren't safe :
it seems that preemptive scheduling takes place during memory allocation
and I can't see where there could be an allocation (and so a switch) in
a read or a write of an IORef.
Related question : how less performant is a MVar comparated to simple