[Haskell-cafe] Posix IO & Unicode lookup exception

25 Apr 2011

      Hi,

I wanted to see if anyone had an idea about why the following program
results in an exception.  The issue seems to be related to stdin to a
POSIX file descriptors for a subprocess, and GHC's Unicode encoding
lookup.  I've tried to make the program as simple as possible to make
the issue obvious.

Consider:
...
module Pipe where
import System.Process
import System.IO
import System.Posix.IO
main = sequence_ $ replicate 100000 f
f = do
  (Just hin, _, _, prc) <-
    createProcess (shell "./pipe_c.out") { std_in = CreatePipe
                                         , std_out = UseHandle stdout
                                         , std_err = UseHandle stderr}
pin <- handleToFd hin
  _   <- fdWrite pin ("h\n")
  closeFd pin
  waitForProcess prc
and a trivial C program to read in the data (but doing nothing with it):

---------------------------------------
#include 

#define SIZE 10

int main(void) {
  char in[SIZE];

  if(fgets(in, SIZE , stdin) != NULL);

  return 0;
}
----------------------------------------

and executing
...
gcc -Wall -o pipe_c.out pipe_c.c
ghci Pipe.hs
main
  ...
*** Exception: malloc: resource exhausted (out of memory)
iconvOpen ("UTF-8","UTF-8"): resource exhausted (Cannot allocate memory)
My best guess is that the GHC is calling iconv_open()
http://www.kernel.org/doc/man-pages/online/pages/man3/iconv_open.3.html,
but not making a subsequent call to iconv_close()
http://www.kernel.org/doc/man-pages/online/pages/man3/iconv_close.3.html.
 (Actually, my best guess is I'm making a silly mistake, but I'm
having trouble seeing it. :) )

I am running 2.6.35-28-generic (Ubuntu) and GHC 7.0.2, but I've
observed the same issues with GHC 6.12.3.

Lee

[Haskell-cafe] Posix IO & Unicode lookup exception

Lee Pike