Package: libghc-missingh-dev
Version: 1.1.0.3-6+b3
Severity: normal
As described in this thread:
http://thread.gmane.org/gmane.comp.lang.haskell.cafe/99334/focus=99338
The attached testcase will hang after a short while once compiled with
-threaded.
Comment out the "LINE OF DEATH" and it runs as expected.
Apparently hPipeFrom etc's use of System.Log.Logger is the culprit. logM uses
a MVar, and this is a MVar deadlock. But I don't understand exactly why this
happens only with the threaded runtime, or really, why the attempt to use the
MVar
*before* forkProcess causes problems at all.
This also seems disturbingly similar to #624389. In both cases System.Cmd.Utils
falls over under heavy load, or is somehow racy.
-- System Information:
Debian Release: wheezy/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: i386 (x86_64)
Kernel: Linux 3.2.0-2-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages libghc-missingh-dev depends on:
ii ghc [libghc-unix-dev-2.5.1.0-b1af7] 7.4.1-4
ii libc6 2.13-32
ii libffi5 3.0.10-3
ii libghc-array-dev-0.4.0.0-0b32f <none>
ii libghc-base-dev-4.5.0.0-c8e71 <none>
ii libghc-containers-dev-0.4.2.1-7c545 <none>
ii libghc-directory-dev-1.1.0.2-89575 <none>
ii libghc-filepath-dev-1.3.0.0-674b8 <none>
ii libghc-hslogger-dev [libghc-hslogger-dev-1.1.4-94350] 1.1.4+dfsg1-2+b3
ii libghc-hunit-dev [libghc-hunit-dev-1.2.4.2-6a847] 1.2.4.2-2+b1
ii libghc-mtl-dev [libghc-mtl-dev-2.1.1-ae9b4] 2.1.1-1
ii libghc-network-dev [libghc-network-dev-2.3.0.13-6b330] 2.3.0.13-1+b2
ii libghc-old-locale-dev-1.0.0.4-29bd5 <none>
ii libghc-old-time-dev-1.1.0.0-681e9 <none>
ii libghc-parsec3-dev [libghc-parsec-dev-3.1.2-ad4f8] 3.1.2-1+b3
ii libghc-process-dev-1.1.0.1-91185 <none>
ii libghc-random-dev [libghc-random-dev-1.0.1.1-3bece] 1.0.1.1-1+b1
ii libghc-regex-compat-dev [libghc-regex-compat-dev-0.95.1-c 0.95.1-2+b1
ii libgmp10 2:5.0.5+dfsg-2
libghc-missingh-dev recommends no packages.
Versions of packages libghc-missingh-dev suggests:
pn libghc-missingh-doc <none>
pn libghc-missingh-prof <none>
-- no debconf information
--
see shy jo
import System.Cmd
import System.IO
import System.Posix.Process
import Control.Monad
import System.Exit
import System.Cmd
import System.Log.Logger
import System.Posix.IO
import System.Posix.Process
import System.Posix.Signals
import System.Posix.Types
import System.IO
import System.IO.Error
import Control.Concurrent(forkIO)
import Control.Exception(finally)
main :: IO ()
main = forever $
pipeRead ["hello", "world"]
pipeRead :: [String] -> IO ()
pipeRead params = do
print $ "pipeRead in " ++ show (params)
(p, h) <- hPipeFrom "echo" params
print "pipeRead getcontents"
c <- hGetContents h
print $ "got: " ++ c
_ <- getProcessStatus True False $ processID p
print "pipeRead out"
data PipeHandle =
PipeHandle { processID :: ProcessID,
phCommand :: FilePath,
phArgs :: [String],
phCreator :: String -- ^ Function that created it
}
deriving (Eq, Show)
logRunning :: String -> FilePath -> [String] -> IO ()
logRunning func fp args = debugM (logbase ++ "." ++ func) (showCmd fp args)
logbase :: String
logbase = "System.Cmd.Utils"
showCmd :: FilePath -> [String] -> String
showCmd fp args = fp ++ " " ++ show args
warnFail :: [Char] -> FilePath -> [String] -> [Char] -> IO t
warnFail funcname fp args msg =
let m = showCmd fp args ++ ": " ++ msg
in do warningM (logbase ++ "." ++ funcname) m
fail m
hPipeFrom :: FilePath -> [String] -> IO (PipeHandle, Handle)
hPipeFrom fp args =
do pipepair <- createPipe
logRunning "pipeFrom" fp args --- LINE OF DEATH
let childstuff = do dupTo (snd pipepair) stdOutput
closeFd (fst pipepair)
executeFile fp True args Nothing
p <- try (forkProcess childstuff)
-- parent
pid <- case p of
Right x -> return x
Left e -> warnFail "pipeFrom" fp args $
"Error in fork: " ++ show e
closeFd (snd pipepair)
h <- fdToHandle (fst pipepair)
return (PipeHandle pid fp args "pipeFrom", h)
