Generally, you would declare the shared variable in a script then fork a worker or workers to do the separate task, where they would have access to the shared var.

Update: Here's a very simple demo:

use strict; use warnings; use feature 'say';
use Time::HiRes qw/ time usleep /;
use MCE::Shared;

say sprintf '%-5s %-17s %-s', 'PID', 'Time', 'Action';

my $shared = MCE::Shared->condvar(0);
say sprintf '%s %.06f Init val: %s', $$, time, $shared->get;

my $pid = fork;

if ( $pid ) {
    for ( 0 .. 19 ) {
        say sprintf '%s %.06f write: %s', $$, time, $shared->incr;
        usleep 10000;
    }
} else {
    while (1) {
        usleep 50000;
        say sprintf '%s %.06f READ: %s', $$, time, $shared->get;
    }
}

__END__
[download]

$ perl shared.pl

PID   Time              Action
16648 1491411785.712927 Init val: 0
16648 1491411785.713604 write: 1
16648 1491411785.724157 write: 2
16648 1491411785.734731 write: 3
16648 1491411785.745270 write: 4
16648 1491411785.755807 write: 5
16650 1491411785.763780 READ: 5
16648 1491411785.766309 write: 6
16648 1491411785.776740 write: 7
16648 1491411785.787272 write: 8
16648 1491411785.797800 write: 9
16648 1491411785.808273 write: 10
16650 1491411785.814272 READ: 10
16648 1491411785.818806 write: 11
16648 1491411785.829300 write: 12
16648 1491411785.839957 write: 13
16648 1491411785.850539 write: 14
16648 1491411785.861082 write: 15
16650 1491411785.864522 READ: 15
16648 1491411785.871574 write: 16
16648 1491411785.882031 write: 17
16648 1491411785.892612 write: 18
16648 1491411785.903151 write: 19
16648 1491411785.913714 write: 20
16650 1491411785.914756 READ: 20
[download]

Hope this helps!

1nickt++, thank you. Regarding MCE::Shared and when the condition var aspect is not needed, the shared scalar will do the same.

my $shared = MCE::Shared->scalar(0);
[download]

Workers fetch and increment accordingly.

$shared->get;
$shared->incr;
[download]

As of this writing, MCE and MCE::Shared are at 1.827 and 1.823 respectively.

Hi again 1nickt,
Following your advise, I'm now attempting to transform the secondary script, compute.pl, as a single subroutine and make this script exporting the necessary variable and of course its subroutine. If I can achieve this by applying little modifications to it, then it solves my problem in what I believe to be an elegant way.

Since this script was meant to be executed as "perl compute.pl -arg1 arg2 (...) arg10 input_file > output_file", I need to find a corresponding syntax for the file input and output when calling the subroutine.
Exporting variable and subroutine from one script to another is ok, I know how to proceed :)

Thanks again for guiding me in what looks to be the right direction :)