Question

I want to do following things from main thread/process:

1. Communicate to another process using pipe.

2. Create threads to do certain task.

3. Wait for all the threads to complete.

Following is the pseudo code I am trying:

 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();
 }

Code gets stuck when I try to join the thread even though it is joinable.

Am I doing something fundamentally wrong here?
I am using Perl 5.10.0

Answer 1

I don’t have a 5.10.0 with threads compiled to try it, but 5.12.4 hangs at “Iam here”. 5.14.1 runs to completion.

Perl threads have a lot of bugs, but it’s gotten much better in recent years. 5.10.0 is probably going to be full of bugs and the simplest way to solve it (and a lot of problems) is to just upgrade Perl.