use XML::LibXML 1.70; ## for load_html/load_xml/location
my $qstat = 'qstat.xml';
my $dom = XML::LibXML->new(qw/ recover 2 /)->load_xml( location => $qstat );
for my $job ( $dom->findnodes( q{   /job_info/queue_info/Queue-List    } ) ){
    print $job->nodePath, "\n";
    for my $slot ( $job->findnodes( q{   ./job_list/slots    } ) ){
        print $slot->nodePath, "\n";
        print $slot, "\n";
        print $slot->textContent, "\n";
    }
}
__END__
/job_info/queue_info/Queue-List
/job_info/queue_info/Queue-List/job_list/slots
<slots>1</slots>
1