[Israel.pm] Interprocess using Safe Pipes Opens

Shushu Inbar שושו ענבר shushu.i at gmail.com
Thu Aug 2 09:27:20 PDT 2007

Hello Mongers !

I am trying to write some code that will handle several child process at once.
I am working in Linux/Solaris environment, using Perl 5.6.1.

After reading all of the IPC documentation I could find, I came to the
decision that using Safe Pipes Opens
(http://perldoc.perl.org/perlipc.html#Safe-Pipe-Opens)  would be the
right answer for me, since the parent process suppose to update the
childs with information during the execution.

I created a skeleton to try and see how it works, but for some reason
I have a problem - only the last child behaves properly and get the
input sent by the parent.

Help would be appreciated,

Below is the code itself (I guess a little ugly...).


use strict;
use warnings;
use Carp;
use Data::Dumper;
use English '-no_match_vars';
use FileHandle;
$| = 1;

my $no_of_childs = 3;

my @fh;
my $index = 0;
while ($index < $no_of_childs) {
	print "PID $PID\n";
	my $pid;
	$fh[$index]{'fh'} = new FileHandle;
	$pid = $fh[$index]{'fh'}->open("|-");
	if ($pid) { # parent
		$fh[$index]{'pid'} = $pid;
		print "parent pid $PID creating child " . 	$index++ . "\n";
	} else {    # child
		print "child pid $PID creating child " . $index++ . "\n";
		while (1) {
			# Here we will do the child work, and read input from STDIN
			print "$PID checking for input\n";
			my $line = <STDIN>;
			if ($line) {
				print "$PID got something from father !!! $line\n";
			sleep 1;

print Dumper \@fh;

my $fh;

sleep 5;
$fh = $fh[0]{'fh'};
print "send hi to child 1\n";
print $fh "shalom yeled 1";

sleep 2;
$fh = $fh[1]{'fh'};
print "send hi to child 2\n";
print $fh "shalom yeled 2";

sleep 2;
$fh = $fh[2]{'fh'};
print "send hi to child 3\n";
print $fh "shalom yeled 3";

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