karls-mac-mini:monks karl$ ./buks_patch.pl 0.01
processes: 4
fork: 13.8262140750885

karls-mac-mini:monks karl$ ./buks_patch.pl 0.25
processes: 4
fork: 13.9020979404449

karls-mac-mini:monks karl$ ./buks_patch.pl 0.5
processes: 4
fork: 15.0743520259857

karls-mac-mini:monks karl$ ./buks_patch.pl 1.0
processes: 4
fork: 20.0701560974121

##</code><code>##

#!/usr/bin/env perl 

use strict;
use warnings;
use Math::BigInt;
use Parallel::ForkManager;
use Time::HiRes qw ( time );
use feature qw(say);

my $sleep_period = shift;
my $processes    = qx(sysctl -n hw.ncpu);

chomp $processes;

my $pm = Parallel::ForkManager->new($processes);

$pm->set_waitpid_blocking_sleep($sleep_period);

say qq(processes: $processes);

my $start = time;

for my $number ( 1 .. 50 ) {
    $pm->start($number) and next;
    my $factorial = Math::BigInt->bfac(2000) for 1 .. 10;
    $pm->finish(0);
}
$pm->wait_all_children;

say qq(fork: ), time - $start;


##</code><code>##

sub _waitpid_blocking {
    my $self = shift;
    # pseudo-blocking  
    if( my $sleep_period = $self->{waitpid_blocking_sleep} ) {
        while() {
            my $pid = $self->_waitpid_non_blocking;
            return $pid if $pid;
            # sleep $sleep_period;
            select( '','','', $sleep_period );
        }
    }

    return waitpid -1, 0;
}