For the curious, here is a version of TGrep.pm by BrowserUk modified to use MCE. Simply remove or comment out "use threads" if Perl lacks support for threads. Threads is not necessary for MCE::Queue.

package TGrep;
use strict;
use threads;

use MCE;
use MCE::Queue;

our $WORKERS = 4;

sub tgrep(&@) {
    my $workers = $WORKERS;
    my $code = shift;
    my @results;

    my $Qin  = MCE::Queue->new( fast => 1 );
    my $Qout = MCE::Queue->new( queue => \@results );

    my $mce = MCE->new(
       max_workers => $workers, user_func => sub {
          $Qout->enqueue( $code->() ? $_ : () ) while local $_ = $Qin-
+>dequeue;
       }
    )->spawn;

    $Qin->enqueue( map{ ref $_[0] ? @{ $_ } : $_ } @_ );
    $Qin->enqueue( (undef) x $workers );
    $mce->run;

    return wantarray ? @results : \@results;
}

sub import {
    no strict 'refs';
    my $pkg = caller;
    *{ $pkg . '::' . $_ } = *{ $_ } for qw[ tgrep ];
}

1;
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Thus, new results emerges.

# $N = 1e6 (4 workers)

TGrep....: Took 30.264018774 seconds
TGrep MCE: Took 15.292614937 seconds (fast => 0)
TGrep MCE: Took  7.824651003 seconds (fast => 1)
[download]

I was curious about how MCE::Queue compares to Thread::Queue for the demonstration. The fast option is beneficial for an already populated queue.