I am seeing some odd behavior from my code (below), and I'd like some help understanding it. My code is based off the Perl Cookbook Recipe 16.12.

When I first ran the code and hit CTRL C, the SIGINT killed all of the children processes, just like it was supposed to. Then I began having errors that said: cannot create semaphore. No space left on device or something very similar to that. In the process of debugging that, I noticed that CTRL-C no longer killed my child processes.

I'm still not sure I've completely understood what was causing me to run out of shared memory space, although my theory is: I was killing the code after just a few iterations, without using die. And I don't understand why my SIGINT trap isn't killing the child processes.

I appreciate any advice or help anyone can offer.

P.S. If it matters: I'm running this code on Linux Mint 9 and Perl 5.10.1

use strict;
# use warnings;
use Parallel::ForkManager;
use LWP::Simple;
use IPC::Shareable;

my $max_forks = 100;

my $forkman = Parallel::ForkManager->new( $max_forks );
my $count=0;
my %data;
open (URLS, "<url-list.txt"); 
my $count_handle = tie $count, 'IPC::Shareable', undef, {destroy => 1 
+}; 
$SIG{INT} = sub { die "$$ dying\n" };

print "Parent PID is $$\n";
while( my $url = <URLS> ) {
    $forkman->start and next;
    chomp($url);
    fetch($url); 
    $forkman->finish;
}
$forkman->wait_all_children;
close URLS;
print "\n\nDONE.\n";

sub fetch { #html get to test parallel forks
    my $target = shift;
    $count_handle->shlock();
    my $thiscount = $count++;
    $count_handle->shunlock();
    my @header = head("http://$target");
    print "PID: $$, $thiscount: $target - @header\n";
}

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In reply to Shared Memory and Child Processes by Mad_Mac

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