As an "XY answer", why are you running an encoder under Wine? Could you use a native MEncoder build and avoid these problems?

Returning to the question, the important step towards your solution is to note that $pm->start optionally accepts an indentifier, and the callback set with $pm->run_on_finish gets that identifier. An untested partial example:

my @slot_in_use = (0, 0);
my @slot_names = qw/one two/;

sub find_slot () {
  for (my $i = 0; $i < @slot_in_use; $i++)
    { unless ($slot_in_use[$i]) { $slot_in_use[$i] = 1; return $i } }
  die "slot table full";
}

$pm->run_on_finish(sub {
  my ($c_pid, $c_exit, $c_slot) = @_;
  $slot_in_use[$c_slot] = 0; # release slot
});

foreach my $n (@data) {
  my $slot = find_slot;
  $pm->start($slot) and next;
  # ...
  $pm->finish;
}

[download]

Update: Remember how I said "untested"? Stupid variable name error fixed. Using strict does not help if you never run the code at all...

In reply to Re: figuring out Parallel::ForkManager slots by jcb
in thread figuring out Parallel::ForkManager slots by ramicio

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