sub RunThread {
    my $tid = threads->tid;
    my $dbh = DBI->connect("DBD::Pg",...) or die "failed connect";
    my ($x, $y)=@_;
    open (my $fh2, ">/tmp/da-$x-$y") or die "failed in thread $! at iter $x thread $y " ;
    print "$tid : ", fileno( $fh2 ); sleep 1;
    close ($fh2);
    $dbh->disconnect or die "disconnect failed";
}