in reply to Parallel::ForkManager problem

if all you need is passing a boolean ok value from the child to the parent, in Parallel::ForkManager you can use the run_on_finish callback to get the exit code of the child.

As I am the author of Proc::Queue let me use that module instead... 

use Proc::Queue size => 10;

sub whatEver {
  my $list = shift;
  my (%pid, %result);

  foreach my $query (keys %$list) {
    my $pid = fork;
    defined $pid or die "fork failed";
    if (!$pid) {
      my $ok = do_whatever();
      exit (!$ok);
    }
    else {
      $pid{$query} = $pid;
    }
  }
  for my $query (keys %pid) {
    if (waitpid($pid{$query}, 0) > 0) {
      $result{$query} = ! $?
    }
  }
  print Dumper("2", \%result);
}

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Re^2: Parallel::ForkManager problem
by Murcia (Monk) on Mar 28, 2006 at 15:39 UTC
    $result{$query} = ! $? can you explain this! Please
[reply]
      Murcia,
      If you look in perlvar, you will see that $? is the status returned by the last closed pipe. The ! is a way to booleanize it. If it has a non-zero value, it becomes 0 and if it had a 0 value, it becomes 1.

      Cheers - L~R

[reply]
        If you look in perlvar, you will see that $? is the status returned by the last closed pipe.

        well, no, you have stoped reading too soon: 

        $?  The status returned by the last pipe close, backtick
    (``) command, successful call to wait() or waitpid(),
    or from the system() operator.

        [download]
        in my code, it is set to the exit code of the child by waitpid.

        It is negated because by convention, exit code 0 means success and any other value failure. Also because this way I don't have to split $? into the signal part and the exit code: 

        $signal = $? & 255;
$exit_code = $? >> 8;

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        But the problem of scope remains with your module, or?
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