use threads;

my $thread = threads->new(\&mysub, $var1, $var2);

for (;;) {
  # here is an infinite loop
  # print seconds to see where it freezes
}


sub mysub {
  my ($var1, $var2) = (shift, shift);

  eval {
    local $SIG{'ALRM'} = sub { die("stop\n"); };
    alarm(10);

    while (1) { # infinite loop }

    alarm(0);
  };

  if ($@) { print "$@\n"; }
  return;
}