Why do I have to kill?

David Byng David.Byng at bbc.co.uk
Tue Oct 16 11:10:16 BST 2007

It's probably the bcp command that's hanging the child, you could try
replacing system() with open2()
http://search.cpan.org/~nwclark/perl-5.8.8/lib/IPC/Open2.pm then you can
waitpid() on the bcp process.

use IPC::Open2;

my $pid = fork();

	print "I'm the parent [$$] child [$pid]\n";

	waitpid $pid, 0;
elsif(not defined $pid)
	die "Can't fork()";
	print "I'm the child [$$] parent[".getppid()."]\n";

	my($rdr, $wrt);
	my $bcp_pid = open2($rdr, $wrt, 'bcp rest of command');

	waitpid $bcp_pid, 0;


-----Original Message-----
From: london.pm-bounces at london.pm.org
[mailto:london.pm-bounces at london.pm.org] On Behalf Of Chris Jack
Sent: 16 October 2007 10:37
To: london.pm at london.pm.org
Subject: RE: Why do I have to kill?

>On Mon, 15 Oct 2007 16:19:24 +0100, "David Byng" David.Byng at bbc.co.uk 
> waitpid() in parent for child to exit
> http://search.cpan.org/~nwclark/perl-5.8.8/pod/perlfunc.pod#waitpid
Maybe I was a little too terse with the code I posted. The parent does a
waitpid on the child process id. The child process drops down to the
exit(0), but the child process doesn't die and the parent hangs around
forever. I need to do a:
 kill 15, $$;
on the child to get it to die - which I can do but it's ugly, but I
guess I'm obliged to in the absence of any external inspiration. When I
do the kill in the child, the waitpid returns in the parent and all
continues OK.
I don't know how to use the perl debugger to see what's happening in the
child - and there are no obvious END blocks that might be doing anything
and there is way too much other code to start putting debug statements
into - even if I did believe they were likely to help.
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