Re: open3 hangs

IPC::Open3 in order to work in as many platforms as possible has become so complex that its inners are almost inaccessible...

Anyway, you have several options:

Use truss to see where (and why) the script is blocking at the OS level.
Make your own version of open3. For Unix it should be quite simple (see below).
... or use some other CPAN module providing the same functionality (IPC::Run, IPC::Cmd, etc.).

# untested

use POSIX ();
sub my_open3 {
  pipe my($in_c), my($in_p) and
  pipe my($out_p), my($out_c) and
  pipe my($err_p), my($err_c) or croak "unable to create pipes";
  my $pid = fork;
  if (!$pid) {
    defined $pid or croak "fork failed";
    unless (open STDIN, '<&', $in_c and
            open STDOUT, '>&, $out_c and
            open STDERR, '>&, $err_c) {
      warn "redirections failed";
      POSIX::_exit(1);
    do { exec @_ };
    POSIX::_exit(1);
  }
  close $in_c;
  close $out_c;
  close $err_c;
  return ($in_p, $out_p, $err_p, $pid);
}
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Re^2: open3 hangs by stephan_a (Novice) on Feb 20, 2009 at 10:10 UTC
Hi and thanks for your proposal. I have modified my code to use the old-fashioned pipe/fork/exec procedure showing me that `open3` actually is not my problem. Instead `fork` blocks. I did some more investigation and found that forking from a thread can be tricky because one may have to deal with locking issues (fork seems to clone all threads). Now I'm looking for a way to cleanly `fork` from a (Perl) thread and `exec` afterwards. Any ideas? Kind regards, Stephan	[reply] [d/l] [select]
Re^3: open3 hangs by salva (Canon) on Feb 20, 2009 at 10:18 UTC
Instead of forking, try creating a new thread and launching the child via `system`... maybe your libc `system()` call will use a different aproach that doesn't need to lock other threads, for instance, a `vfork` based one.	[reply] [d/l] [select]
Re^4: open3 hangs by stephan_a (Novice) on Feb 20, 2009 at 10:52 UTC
Hmmm… The documentation (perlfunc) says: Does exactly the same thing as "`exec LIST`", except that a fork is done first, and the parent process waits for the child process to complete.	[reply] [d/l]