#! perl -slw
use strict;
use threads;
use threads::shared;
use Thread::Queue;
use Math::BigInt;
use Time::HiRes qw[ time ];
use Data::Dump qw[ pp ];
use feature qw(say);

my %result : shared;

sub process {
    my $Q = shift;
    while( my $number = $Q->dequeue ) {
        my $factorial = factorial($number);
        lock %result;
        $result{$number} = $factorial->bstr;
    }
}

sub factorial {
    my $number = shift;
    Math::BigInt->bfac($number);
}

my $start = time;

my $Q = new Thread::Queue;
$Q->enqueue( 1000..2000, (undef) x 4 );

my @threads = map { threads->create( \&process, $Q ); } 1 .. 4;

$_->join for @threads;
my $end = time;
printf "Took %.6f seconds\n", $end - $start;