I just learning how to use SIGALRM, and have run into a little problem that I need your help with. The following code runs as expected on Unix (solaris) and on an MS Win XP desktop, but fails on MS Win Server 2003 R2. I understand that it's a mistake to intermix sleep and alarm, but it's sufficient for this example (the "real" code doesn't "sleep", and has the same problem).

#!/usr/bin/perl -w
use strict;
use warnings;

$|                  = 1;
$SIG{'ALRM'}        = '_ALARM';
$SIG{'QUIT'}        = '_QUIT';

my  $s_parent       = 0;
my  $patience_level = 5;
my  $doddling_time  = 10;

my  $child_pid      = fork();
if ($child_pid) {               # If parent process
    $s_parent       = 1;
    print "Parent: [tapping toe] You have $patience_level seconds to f
+inish your homework ($child_pid)!\n";
    alarm $patience_level;
    my $job_well_done = wait();
    print "Parent: Well, that's over ($job_well_done).\n";
} elsif (defined $child_pid) {  # If child process
    print "Child.: [doddling...] OK, OK, just $doddling_time more seco
+nds, ...please!?!\n";
    sleep $doddling_time;
  # The following is unlikely if patience_level < doddling_time
    print "Child.: Nana-nana-na-na - all finished ($$).\n";
    exit;
} else {                        #   Error on fork
    die "!!! Failed to fork !!!..: $!\n";
}

print "The end.\n";
exit;

sub _ALARM {
    if ($s_parent) {
        print "Parent: Time's up kiddo...\n";
        if (kill 0, $child_pid) {
            print "Parent: $child_pid is gonna get spanked!\n";
            my $spank = kill 'QUIT', $child_pid;
            print "Pain level: $spank\n";
        } else {
            warn  "$child_pid has hidden!\n";
        }
    } else {
        print "Child.: Nobody expects the Spanish Inquisition!\n";
    }
}

sub _QUIT {
    print "Child.: Argh! You didn't have to spank me! ($$)\n";
    exit;
}

[download]

I expect to see this output:

Parent: [tapping toe] You have 5 seconds to finish your homework (-670
+8)!
Child.: [doddling...] OK, OK, just 10 more seconds, ...please!?!
Parent: Time's up kiddo...
Parent: -6708 is gonna get spanked!
Pain level: 1
Child.: Argh! You didn't have to spank me! (-6708)
Parent: Well, that's over (-6708).
The end.

[download]

But on the server in question, I see:

Parent: [tapping toe] You have 5 seconds to finish your homework (-588
+0)!
Child.: [doddling...] OK, OK, just 10 more seconds, ...please!?!
Child.: Nana-nana-na-na - all finished (-5880).
Parent: Well, that's over (-5880).
The end.

[download]

My apologies in advance to the non-spankers out there - this was just an effort to make light of a situation that's been frustrating. No children were actually harmed in writing (or executing) this code ;).

Thanks again for your help!

In reply to alarm not triggering SIGALRM on Windows 2003 by perlofwisdom

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