use POSIX qw( WNOHANG );

# Returns false if alive.
# Returns true if dead. (Reaps and sets $?)
# Throws expection on error. (Sets $!)
sub is_child_dead {
    my ($pid) = @_;
    my $rv = waitpid($pid, WNOHANG);
    die("waitpid: $!\n") if $rv == -1;
    return $rv;
}