#!/usr/bin/perl

use warnings;
use strict;
use Data::Dumper;

use threads ( stack_size => 4096 );
use threads::shared;
use Thread::Queue;

my %count;
my @buffer : shared;
my $maxthreads = 5;

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

my @threads = map threads->create( \&inc, $queue, \@buffer ), 1 .. $maxthreads;

# there are way more lines than this but anyway...
for my $i ( 1 .. 500 ) {

    # this just represents that I've found a pair and want to run the sub
    if ( $i % 50 == 0 ) {

        # push the pair in the queue
        $queue->enqueue("$i:2");
    }
    empty_buffer( \@buffer ) if @buffer;
}

$queue->enqueue( (undef) x $maxthreads );
$_->join for @threads;

empty_buffer( \@buffer ) while @buffer;

print Dumper \%count;

sub inc {
    my ( $queue, $arrayref ) = @_;
    my $tid = threads->tid;
    while ( my $param = $queue->dequeue ) {

        # long subroutine using passed params
        # pausing for effect!
        # this simulates that the sub takes a while to run
        sleep( 2 + rand 5 );

        # let you know something is happening
        print "Thread# $tid | Parameter: $param\n";

        my ( $p1, $p2 ) = split /:/, $param;

        # add it to the buffer
        lock $arrayref;
        push @{$arrayref}, "$p1:$p2:" . $p1 * $p2;
    }
}

sub empty_buffer {
    my $buffref = shift;
    my ( $p1, $p2, $result ) = split /:/, shift @{$buffref};
    $count{$p1}{$p2} = $result;
}