use strict;
use warnings;
use MCE::Loop;
use Time::HiRes 'time';

my @tokens = ('aaa'...'zzz');
my $start  = time;

sub build_regex {
    my ($token) = @_;
    chop $token;
    $token .= 'a';
}

MCE::Loop->init(
    chunk_size  => 1,
    max_workers => 4,
);

my %result = mce_loop {
    my $token = $_;
    my $regex = build_regex($token);
    my @line_results = grep { $_ ne $token and /$regex/ } @tokens;
    MCE->gather( $token => \@line_results ) if @line_results;
} @tokens;

MCE::Loop->finish;

printf "duration: %0.03f seconds\n", time - $start;
print scalar(keys %result), "\n"; # 16900