use strict;
use warnings;
use 5.012;

use threads;
use Thread::Queue;


my $q = Thread::Queue->new;

sub do_stuff {
    my $id = threads->tid;
    my $data;

    while ($data = $q->dequeue) {
        #Process data:
        sleep rand(5);

        say "$id: Done with: '$data'. ",
            'Going back to q to get more data.';
    }

    say "$id: No more data in q.  Quitting...";

}

my $max_threads = 5;
my @threads = map { threads->create(\&do_stuff) } 
                  1 .. $max_threads
                  ;

#All threads are now blocking on dequeue() and waiting for data.

my @data = qw(

    hi      hello   greetings
    what    where   how
    world   earth   gia
    mars    venus   jupiter
);

for my $data (@data) {
    $q->enqueue($data);
}

#Make all threads exit their while loops:
for (1 .. $max_threads) {
    $q->enqueue(undef);
}


#Don't end the program until all threads have finished:
for my $thr (@threads) {
    $thr->join
}

--output:--
1: Done with: 'greetings'. Going back to q to get more data.
5: Done with: 'hello'. Going back to q to get more data.
3: Done with: 'what'. Going back to q to get more data.
5: Done with: 'world'. Going back to q to get more data.
5: Done with: 'earth'. Going back to q to get more data.
4: Done with: 'how'. Going back to q to get more data.
2: Done with: 'hi'. Going back to q to get more data.
1: Done with: 'where'. Going back to q to get more data.
1: No more data in q.  Quitting...
5: Done with: 'mars'. Going back to q to get more data.
5: No more data in q.  Quitting...
3: Done with: 'gia'. Going back to q to get more data.
3: No more data in q.  Quitting...
4: Done with: 'venus'. Going back to q to get more data.
4: No more data in q.  Quitting...
2: Done with: 'jupiter'. Going back to q to get more data.
2: No more data in q.  Quitting...