[Haskell-cafe] all threads are blocked by recvFrom

Hello, I have a problem with building multithreaded UDP server. If main thread is waiting for new request in recvFrom all other threads are blocked too. I've checked every variant with forkIO,forkOS,-threaded etc, nothing's helped. After reading GHC docs I've understood this is happened becouse foreign function call from recvFrom (network library) is marked to be unsefe, so it's execution blocks every other thread. How can I resolve it? Thank you. Vitaliy.