I had always wanted to share a solution using MCE which comes with a sequence generator. This allows one to use a pool of workers seamlessly while iterating through a sequence of numbers.

The first example is a modified version of the demonstration by BrowserUk.

use strict;
use threads;
use threads::shared;
use MCE::Flow;
use Math::BigInt;
use feature qw(say);

my %result : shared;

mce_flow_s { chunk_size => 1, max_workers => 4 }, \&process, 1, 1000;

for my $key ( sort{ $a <=> $b } keys %result ) {
    say "$key => ", $result{ $key }->bstr;
}

sub process {
    my $number    = $_;
    my $factorial = factorial($number);
    $result{$number} = shared_clone( $factorial ); ## clone the object
}

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

The next example requires the upcoming MCE 1.7 release, currently residing in GitHub. Notice the use of MCE::Shared and the capital letter S in Shared for the variable attribute.

use strict;
use MCE::Flow;
use MCE::Shared;
use Math::BigInt;
use feature qw(say);

my %result : Shared;

mce_flow_s { chunk_size => 1, max_workers => 4 }, \&process, 1, 1000;

for my $key ( sort{ $a <=> $b } keys %result ) {
    say "$key => ", $result{ $key }->bstr;
}

sub process {
    my $number    = $_;
    my $factorial = factorial($number);
    $result{$number} = $factorial;  # the object is shared automatical
+ly
}

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

Both complete in the same time frame. Threads is not required to run MCE::Shared as it supports threads and processes alike. Thus, one may include threads if desired.

Init is another way to specify MCE options.

MCE::Flow::init {
   chunk_size => 1,
   max_workers => 4,
};

mce_flow_s \&process, 1, 1000;
[download]

Kind regards, Mario