Quoting perlwin32: Signal handling may not behave as on Unix platforms (where it doesn't exactly "behave", either :). For instance, calling die() or exit() from signal handlers will cause an exception, since most implementations of signal() on Win32 are severely crippled. Thus, signals may work only for simple things like setting a flag variable in the handler. Using signals under this port should currently be considered unsupported.

The kill command does not really send a signal under Win32 but as on all systems, SIGKILL is not something you can catch and handle. Your process never really "sees" that signal, it just gets stopped and removed from the set of active processes.

Update: I just saw you're not sending a SIGKILL, so it seems that the signal emulation across processes on Win32 is just SIGKILL no matter what number you hand to kill.

To add to what Corion said, Windows doesn't have signals. Anything you see in Perl is an emulation. As with almost all emulations, there are flaws and limitations. Windows is based around messages sent to windows (due to its origins as a windowing environment running over DOS).

That means you'll probably have better luck by using Windows calls directly. WaitForSingleObject and family allows you to wait for child processes to die by waiting on a process handle. This is can be obtained when creating the child and by other means. It supports a timeout.

As ikegami points out, signals don't exist on win32, so what this is detailing is just an emulation. You can only use it from and between perl programs; and attempting to use it for anything other than 'Is the process still alive'; and 'kill process with extreme prejudice'; really doesn't work. #

I have a postit stuck on my wall that reads:

Win32 trappable sigs: BREAK/21, INT/2, QUIT/3, TERM/15; Others (except 0) always fatal!

Going by the faded color of the postit, it's probably at least 2 years old. I do remember it was frustratingly hard to verify this information. Anyone who wants to try might find this code useful as a starting point.

SigCheck.pl

#! perl -slw
use strict;
use Config;

$|++;

sub startKid {
    warn "starting kid\n";
    my $pid = system 1, '/perl/bin/perl.exe trapSigs.pl' or die $!;
    sleep 0;
    warn "starting kid\n";
    return $pid;
}

my $pid = startKid;

for my $signo ( sort {$a<=>$b} split ' ', $Config{ sig_num } ) {
    warn "Skipping $signo\n\n" and next if $signo == 15 or $signo == 2
+1;
    warn "Trying $signo\n";
    warn "kill $signo, $pid returned: ", kill( $signo, $pid ), "\n";
    for( 1 .. 3 ) {
        my $rv = kill 0, $pid;
        print "Attempt $_ at kill 0, $pid returned: ", $rv;
        last unless $rv;
        sleep 1;
    }
    if( kill 0, $pid ) {
        warn "signal no: $signo was non-fatal\n\n";
    }
    else {
        warn "signal no: $signo was fatal\n\n";
        $pid = startKid;
        warn "Restarted kid: $pid\n";
        sleep 1;
    }
}
[download]

TrapSigs.pl

#! perl -slw
use strict;
use Config;

print <>;
close STDIN;


my @sigs = split ' ', $Config{ sig_name };
shift @sigs;

for ( @sigs ) {
    warn "Installing signal handler for $_\n";
    eval qq[\$SIG{ $_ } = sub{ warn "Signal $_ received\n"; } ];
}

my $count;
while( 1 ) {
    $count += 1 for 1.. 1e6;
    warn $count;
    sleep 3;
}
[download]