Hello, I have this very simple program that executes an external program, reads its output and prints it (the program is "date"). The readings is done with pipes. The problem is that memory usage constantly increases over time. Profiling does not show garbage collection of any sort. File descriptors and handles seem to be properly closed. Still I cannot find out where the problem lays. Can it be related to the fact that runProcess closes the handles so that the write file descriptor of the pipe is left open? using a "closeFd w" after runProcess gives a Bad fd error. Moreover, fdToHandle "converts" the fd into a handle, so I presume that closing the second should be enough. And indeed removing or inserting rc <- handleToFd rh and closeFd rc doesn't change anything. Thanks for your help. Andrea The code: ---------------- module Main where import System.Process import System.Posix.IO import System.IO import Control.Concurrent runComLoop :: String -> IO () runComLoop command = do (r,w) <- createPipe wh <- fdToHandle w hSetBuffering wh LineBuffering p <- runProcess command [] Nothing Nothing Nothing (Just wh) (Just wh) rh <- fdToHandle r str <- hGetLine rh rc <- handleToFd rh hClose rh closeFd rc -- get and print the status of handles swh <- hShow wh srh <- hShow rh putStrLn $ show swh putStrLn $ show srh putStrLn str threadDelay $ 100000 * 1 runComLoop command main = runComLoop "date"