Re: [Haskell-cafe] Why do "unsafe" foreign calls block other threads?

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Just think of "unsafe" in relation to "unsafeIndex" or something. It's faster, but you have to be sure the index is in bounds. Yes, but the whole reason to use "unsafe" is to get higher performance at the cost of safety.  If the result of calling an "unsafe" foreign function is that you *lose* performance because the other threads have to be halted first, then this seems to defeat the whole point of marking a call as "unsafe" in the first place.

That's why the function has to return soon and shouldn't do a lot of work.