Dear Fellow Monks,

I have the a task that sums up the results of two functions. It looks like this: 
              Total Sum = Function_1 + Function_2

[download]
Now these two functions can be executed in parallel way. Meaning that the output of Function_1 doesn't depend on Function_2 or vice versa. The problem is that these functions require a very time consuming process. That's why I need it to run in parallel.

For simplicity sake, the function basically takes a number as an upperbound of series of value and perform some arithmetic on them. The overall non-parallel and very time consuming process can be seen in the current code of mine:

#!/usr/bin/perl -w
use strict;

sub Function_1 {
    my $up_bound1 = shift;
    
    my $total_f1;
    foreach  my $in (0..$up_bound1) {
        $total_f1 += $in/3;
    }
    
    return $total_f1;
}

sub Function_2 {
    my $up_bound2 = shift;
    
    my $total_f2;
    foreach  my $in (0 .. $up_bound2) {
           $total_f2 += $in;
    }
    
    return $total_f2;
}

## Begin main process

my $up_bound = 10;
my $sum = Function_1($up_bound)+Function_2($up_bound);
print "$sum\n";

[download]
Which yields: 73.33333333333333
To speed up the code above, I am trying to use POE, especially running F1 and F2 in parallel. The main idea is this: And I would like to pack them inside a subroutine that returns the single final summed value.

This is the first time I am using it. So please kindly bear with me. Here is the sample code I have, in which I'm totally lost. Not knowing how to go about it: 

#!/usr/bin/perl
use warnings;
use strict;
use POE;

my $up_bound = 10;

my $final_result = parallel_with_poe($up_bound);


sub parallel_with_poe {

$ubound = shift;
POE::Session->create(
    inline_states => {

     # How can I pass the parameter correctly here?
         _start         => Function_1($_KERNEL,$ubound);
         to_wait        => sub { $_[KERNEL]->(delay (tick=>2)); }
         run_function_2 => Function_2($_KERNEL,$ubound);

     # This ain't right also, I don't know
     # how to pass  the above result into the function
     _stop          => final_sum($_KERNEL,$ubound); 
                 
    },
);

$poe_kernel->run();
return;  # how to return the final value?
#exit(0);
}


sub final_sum {
    my ($kernel,$ans_of_f1, $ans_of_f2) = @_;
    my $sum = $ans_of_f1+$ans_of_f2;
    return $sum;
}


sub Function_1 {
    my ($kernel_f1, $up_bound1) = @_;
    
    my $total_f1;
    foreach  my $in ( 0 .. $up_bound1) {
            $total_f1 += $in/3;
    }
    return $total_f1;
}

sub Function_2 {
    my ($kernel_2,$up_bound2) = @_;
    
    my $total_f2;
    foreach  my $in (0 .. $up_bound2) {
           $total_f2 += $in;
    }
    return $total_f2;

[download]
Thus, I humbly seek for enlightment from my fellow monks.

Regards,
Edward

In reply to My First POE - Simple Parallel Programming by monkfan

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