RE: [Haskell-cafe] Re: Bound threads

On 26 February 2005 12:14, Marcin 'Qrczak' Kowalczyk wrote:

Wolfgang Thaller writes:

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Since the main thread is bound, and unbound threads are never executed on an OS thread which has some Haskell thread bound, this would imply that when the main thread spawns a Haskell thread and they synchronize a lot with each other using MVars, the synchronization needs OS-thread synchronization - the threads will not execute on a the same OS thread.

Correct.

Is it important which thread executes Haskell code (I bet no) and unsafe foreign calls (I don't know)? If not, couldn't the same OS thread execute code of both threads until a safe foreign call is made?

Actually in a bound thread, *all* foreign calls must be made using the correct OS thread, not just the safe ones. So your scheme would involve a context switch at every foreign call, which would end up being rather expensive. It's certainly a legitimate implementation, but I suspect not one that would lead to good performance. Cheers, Simon