Re: Waiting on Sockets or File Descriptors

Simon Marlow writes:

When you compile your program with -threaded, "safe" FFI calls don't block other threads, but "unsafe" calls still do. Basically a "safe" FFI call releases the lock on the RTS so other Haskell threads can continue to run [...].

Thanks for the clarification. If I understood this right, then I can use forkIO to run a "safe" FFI function which blocks, but in the threaded RTS this will not block all other FFI calls. So what happens in the non-threaded RTS? Now the blocking yet "safe" FFI invocation _would_ block other FFI calls but not evaluation of "pure Haskell" code. Is that right? Peter