[…. code …]

my $sigset_new = POSIX::SigSet->new();
my $sigset_old = POSIX::SigSet->new();

sigprocmask(SIG_BLOCK, $sigset_new, $sigset_old);

if ($sigset_old->ismember(SIGALRM))
{
$sigset_new->addset(SIGALRM);
sigprocmask(SIG_UNBLOCK, $sigset_new);
}
else
{
# do nothing
}

eval {

$SIG{ALRM}=sub{
   sigprocmask(SIG_BLOCK, $sigset_new, $sigset_old);
   exit;
};

alarm ($timer);

   for (@mylist)
   {
   my $cmd= "perl process_$_.pl args";  # tried with trailing & too
   system($cmd);
   }

alarm (0);
};

[ … more code …]