perl: to avoid zombie process

#!/ms/dist/perl5/PROJ/core/5.8/bin/perl -w
use strict;
use diagnostics;

$SIG{CHLD} = 'IGNORE';
#this is only to see what's in this hash
while (my ($key, $value) = each %SIG)
{
    print $key." --> ".$value."\\n";
}

my $rret=fork;


if($rret)
{
    print "this is parent process and id is ".$$."\\n";
    sleep 10;
}
elsif ($rret == 0)
{
    print "this is child process and id is ".$$." and it's parent process id is ".getppid."\\n";
}
else
{
    die($!);
}