Thank you all. But there are two things that remain obscure: First, there is my situation: int the main thread, I call to some C functions binded through FFI. All of them are marked 'unsafe', except one, which is internally supposed to make pauses with 'usleep'. I then execute in another haskell thread (with forkIO) some pure haskell actions. I then compile with the threaded RTS, and let at run the default behaviour which is to use one core. Question 1) What happens to the "unsafe" C functions? I that simply that the threaded RTS is unable to prevent them from blocking haskell threads (which in my case is a problem only for the function which pauses, since other C calls are fast)? Or they could provoke a hazardous issue, so I have to mark all the C functions as "safe" (which will be much slower) because ? Question 2) In the Control.Concurrent documentation, I understood that forkIO creates unbound threads whereas forkOS creates bound threads, but what is not very clear is: when does GHC threaded runtime launches as bound instead of unbound if this one has been started with forkIO? When it detects the thread calls to a C function? When it detects it calls to a "safe" C function (*)? When it detects another thread calls to a (safe) C function (which is my case)? (*) according to documentation it would be this case. However as I said my C calls are done in the MAIN thread. The other thread just executes casual haskell operations, however it is not blocked, which makes me think that even if I launch it with forkIO, it is launched as an bound thread. Bulat Ziganshin-2 wrote:
Hello Yves,
Thursday, February 18, 2010, 2:10:42 AM, you wrote:
Okay! So under UNIX, haskell threaded runtime uses pthreads, if I well understood.
not exactly. it still uses lightweight (green) threads, but starts additional OS threads as required to keep N haskell threads running. it's very smart
To sum up, in order to achieve what I want, I have no other choice than compiling with '-threading' and importing as 'safe' the functions which can make a 'sleep'.
Thanks!
----- Yves Parès Live long and prosper -- View this message in context: http://old.nabble.com/Threading-and-FFI-tp27611528p27635260.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.