Hello Einar, Monday, December 12, 2005, 8:43:15 AM, you wrote: EK> It seems that opening the same file multiple times (one writer EK> and multiple readers) is not supported at least on *nix with EK> GHC. I want to use one Handle to use append data till the EK> end of the file while other Handles perform random access EK> IO with seeks on the file. EK> Sharing the same Handle for all the threads is not possible EK> since they perform seeks and may thus mess each other up. EK> Hiding the Handle behind a mutex would limit concurrency EK> more than I like. may be you can use some tricks, for example read large binary block from file inside mutex and then parse it in memory? EK> Thus I wanted to open multiple Handles to the file, but EK> this seems quite hard. My best guess is to create a function EK> like: EK> #ifdef mingw32_HOST_OS EK> openUnlocked fn mode = openBinaryFile fn mode EK> #else EK> openUnlocked fn mode = withMVar mutex $ do EK> h <- openBinaryFile fn mode EK> fd <- handleToFd h EK> unlockFile $ fromIntegral fd EK> return h are you read implementation of handleToFd? -- | Extracts the 'Fd' from a 'Handle'. This function has the side effect -- of closing the 'Handle' and flushing its write buffer, if necessary. handleToFd :: Handle -> IO Fd handleToFd h = withHandle "handleToFd" h $ \ h_ -> do -- converting a Handle into an Fd effectively means -- letting go of the Handle; it is put into a closed -- state as a result. let fd = haFD h_ flushWriteBufferOnly h_ unlockFile (fromIntegral fd) -- setting the Handle's fd to (-1) as well as its 'type' -- to closed, is enough to disable the finalizer that -- eventually is run on the Handle. return (h_{haFD= (-1),haType=ClosedHandle}, Fd (fromIntegral fd)) there is also dupHandle but i'm not sure that it will help another possibility is to work with FDs directly. i can give you a mini-lib, which emulates Handle-like functions on FDs, but it will be very inefficient at char-by-char i/o -- Best regards, Bulat mailto:bulatz@HotPOP.com