How do you test code that uses shared variables with threads::shared?

Testing code that utilizes shared variables with threads::shared in Perl can be a bit tricky due to the nature of thread safety and data consistency. Below is a simple example demonstrating how to work with shared variables between threads and how to test them effectively.

Example: Shared Variables with threads::shared

use strict;
use warnings;
use threads;
use threads::shared;

# Shared variable
my $shared_var : shared = 0;

# Thread subroutine
sub incrementer {
    for (1..1000) {
        lock($shared_var); # Lock the shared variable for thread safety
        $shared_var++;
    }
}

# Create threads
my @threads;
for (1..5) {
    push @threads, threads->create(\&incrementer);
}

# Wait for threads to finish
foreach my $thread (@threads) {
    $thread->join();
}

# Print the final value of the shared variable
print "Final Value of Shared Variable: $shared_var\n";