On Thu, Jan 08, 2004 at 09:33:29AM -0800, Hal Daume III wrote:
> Hi,
>
> I'm using POpen to shell out to a command several hundreds or thousands of
> times per call (none of them simultaneous, though, this is completely
> serial). After running my program for a while, I get:
>
> Fail: resource exhausted
> Action: forkProcess
> Reason: Resource temporarily unavailable
>
> which basically seems to be telling me that the program hasn't been
> closing the old processes, even though they're definitely not in use
> anymore.
>
> Does anyone have any suggestions how to get around this?
I had a similar problem, and finally I created my own solution that
doesn't leave zombies and doesn't block when the launched process writes
too much to stderr.
I tested it in GHC 6.0. For 6.2 you'd have to change the use of
forkProcess.
Usage:
launch :: String -> [String] -> String -> IO (ProcessStatus, String, String)
(status, out, err) <- launch prog args progInput
Example:
*Shell> (status, out, err) <- launch "tr" ["a-z", "A-Z"]
(unlines (replicate 10000 "Haskell"))
*Shell> status
Exited ExitSuccess
*Shell> length out
80000
*Shell> mapM_ putStrLn (take 10 (lines out))
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
HASKELL
Best regards,
Tom
--
.signature: Too many levels of symbolic links
module Shell where
import System.Posix.Process
import System.Posix.IO
import Control.Concurrent
import IO
launch :: String -> [String] -> String -> IO (ProcessStatus, String, String)
launch prog args inputStr = do
(childIn, parentIn) <- createPipe
(parentOut, childOut) <- createPipe
(parentErr, childErr) <- createPipe
forkProcess >>= \pid -> case pid of
Nothing -> do -- child
closeFd parentIn
closeFd parentOut
closeFd parentErr
closeFd 0 -- FIXME: What if some of 0,1,2 are already closed?
closeFd 1
closeFd 2
childIn `dupTo` 0
childOut `dupTo` 1
childErr `dupTo` 2
closeFd childIn
closeFd childOut
closeFd childErr
executeFile prog True args Nothing
fail "launch: executeFile failed"
Just child -> do -- parent
closeFd childIn
closeFd childOut
closeFd childErr
input <- fdToHandle parentIn
output <- fdToHandle parentOut
err <- fdToHandle parentErr
outputCS <- hGetContents output
errCS <- hGetContents err
outputMV <- newEmptyMVar
errMV <- newEmptyMVar
inputMV <- newEmptyMVar
forkIO $ hPutStr input inputStr >> hClose input >> putMVar inputMV ()
forkIO $ foldr seq () outputCS `seq` hClose output >> putMVar outputMV ()
forkIO $ foldr seq () errCS `seq` hClose err >> putMVar errMV ()
takeMVar outputMV
takeMVar errMV
takeMVar inputMV
mStatus <- getProcessStatus True False child
case mStatus of
Nothing -> fail "launch: can't get child process status"
Just stat -> return (stat, outputCS, errCS)
_______________________________________________
Glasgow-haskell-users mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
