use strict;
use warnings;

# Run on UNIX machines with 32+ GiB of RAM.
# Otherwise, remove the -use_dev_shm argument.
# Beware, consumes 14 GiB in temp dir.

use MCE::Signal qw[ $tmp_dir -use_dev_shm ];
use Time::HiRes qw[ time ];

use MCE::Loop;
use MCE::Shared;

die "Not UNIX OS\n" if $^O eq 'MSWin32';

# usage: script.pl > out

my $start = time;
my $c_shared = MCE::Shared->scalar(0);

MCE::Loop::init {
    max_workers => 6,
    chunk_size  => 1
};

# loop through desired combinations	
mce_loop_s {
    my ($p0,$c) = ($_,0);
    my ($p1,$p2,$p3,$p4,$p5,$p6,$p7,$p8,$p9,$p10);
    open my $fh, ">", "$tmp_dir/".MCE->chunk_id();

    for ($p1=0; $p1<=1; $p1+=0.2){
        for ($p2=0; $p2<=1; $p2+=0.2){
            for ($p3=0; $p3<=1; $p3+=0.2){
                for ($p4=0; $p4<=1; $p4+=0.2){
                    for ($p5=0; $p5<=1; $p5+=0.2){
                        for ($p6=0; $p6<=1; $p6+=0.2){
                            for ($p7=0; $p7<=1; $p7+=0.2){
                                for ($p8=0; $p8<=1; $p8+=0.2){
                                    for ($p9=0; $p9<=1; $p9+=0.2){
                                        for ($p10=0; $p10<=1; $p10+=0.2){
                                            #-------------
                                            print $fh "$p0\t$p1\t$p2\t$p3\t$p4\t$p5\t$p6\t$p7\t$p8\t$p9\t$p10\t1\t1\n";
                                            ++$c;
                                            #-------------
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    close $fh;
    $c_shared->incrby($c);

} 0, 1, 0.2;  # p0: seq_beg, seq_end, seq_step

MCE::Loop::finish();

system("cat $tmp_dir/[1-6]; rm -fr $tmp_dir");

printf STDERR "Took: %0.3f seconds [%ld]\n", time() - $start, $c_shared->get();


##</code><code>##

use strict;
use warnings;

# Run on UNIX machines with 32+ GiB of RAM.
# Otherwise, remove the -use_dev_shm argument.
# Beware, consumes 14 GiB in temp dir.

use MCE::Signal qw[ $tmp_dir -use_dev_shm ];
use Time::HiRes qw[ time ];

use MCE::Loop;
use MCE::Shared;

die "Not UNIX OS\n" if $^O eq 'MSWin32';

# usage: script.pl > out

my $start = time;
my $c_shared = MCE::Shared->scalar(0);

MCE::Loop::init {
    max_workers => 6,
    chunk_size  => 1
};

# loop through desired combinations	
mce_loop_s {
    my $p0 = $_;

    MCE::Loop::init {
        max_workers => 6,
        chunk_size  => 1
    };

    $tmp_dir .= "/".MCE->chunk_id();
    mkdir $tmp_dir;

    mce_loop_s {
        my ($p1,$c) = ($_,0);
        my ($p2,$p3,$p4,$p5,$p6,$p7,$p8,$p9,$p10);
        open my $fh, ">", "$tmp_dir/".MCE->chunk_id();

        for ($p2=0; $p2<=1; $p2+=0.2){
            for ($p3=0; $p3<=1; $p3+=0.2){
                for ($p4=0; $p4<=1; $p4+=0.2){
                    for ($p5=0; $p5<=1; $p5+=0.2){
                        for ($p6=0; $p6<=1; $p6+=0.2){
                            for ($p7=0; $p7<=1; $p7+=0.2){
                                for ($p8=0; $p8<=1; $p8+=0.2){
                                    for ($p9=0; $p9<=1; $p9+=0.2){
                                        for ($p10=0; $p10<=1; $p10+=0.2){
                                            #-------------
                                            print $fh "$p0\t$p1\t$p2\t$p3\t$p4\t$p5\t$p6\t$p7\t$p8\t$p9\t$p10\t1\t1\n";
                                            ++$c;
                                            #-------------
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }

        close $fh;
        $c_shared->incrby($c);

    } 0, 1, 0.2;  # p1: seq_beg, seq_end, seq_step

    MCE::Loop::finish();

} 0, 1, 0.2;  # p0: seq_beg, seq_end, seq_step

MCE::Loop::finish();

system("cat $tmp_dir/$_/[1-6]; rm -fr $tmp_dir/$_") for 1..6;

printf STDERR "Took: %0.3f seconds [%ld]\n", time() - $start, $c_shared->get();


##</code><code>##

Combinatorics : 459.752 seconds
    6 workers : 145.695 seconds
   36 workers : 109.134 seconds <- my CPU has 8 cores