I realize that this is an old thread but I ran across this trying to solve a similar problem: run a specific number of threads to work on a set of issues. I thought it might be useful for others to know the correct implementation of Tanktalus' suggestion.

Basically, there were two issues that took me a while to sort out: firstly, the newly created threads are detached, which makes them impossible to join later; secondly (much less important), adding undef as a queue item isn't necessary when using dequeue_nb instead of dequeue.

The code that actually works for me looks like this:

#! /usr/bin/perl
use threads;
use Thread::Queue;

my $q = Thread::Queue->new();    # A new empty queue
# Send work to the threads
$q->enqueue($_) for @ARGV;

# Worker threads
my $thread_limit = 8; 

my @thr = map {
    threads->create(sub {
        while (defined (my $item = $q->dequeue_nb())) {
            doStuff($item);
        }
    });
} 1..$thread_limit;
 
# terminate.
$_->join() for @thr;
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