如何让DBD::Pg可靠地超时?

#!/usr/bin/perl

use strict;
use warnings;

use DBI;
use Sys::SigAction qw( set_sig_handler );

my $dbh = DBI->connect('dbi:Pg:dbname=dc');

eval {
    my $h = set_sig_handler('ALRM', sub { die "timeout\n" });
    eval {
        alarm 1;
        my $sth = $dbh->prepare("SELECT pg_sleep(10)");
        print "Before execute\n";
        $sth->execute;
        print "After execute\n";
        $sth->finish;
    };
    alarm 0;
    die "$@" if $@;
};
die "$@" if $@;
print "Finished\n";