use threads;
 use IO::Handle;
 sub dummy {
      print "\n!!!!". $$;
      return 0;
 }

 open($handle, "| cat -v") || die "Unable to open connection to BT Driver: $!\n";

 $handle->autoflush(1);

 #close $handle; If I uncomment this, threads can be joined. But I don't want to terminate this child process.

 $thr2 = threads->create(\&dummy);
 sleep 2;
 print "\n$thr2";
 foreach $thr (threads->list(threads::joinable))
 {
      print "\nIam here";
      print "\n!!!". $thr;
      $thr->join();
 }