#!/usr/bin/perl

$|=1;

use strict;
use warnings;

use threads;
use threads::shared;
use Data::Dumper;

# Global vars

# Maximum working threads
my $MAX_THREADS = 20;

# Flag to inform all threads that application is terminating
my $TERM:shared=0;

# Prevents double detach attempts
my $DETACHING:shared;

# Signal handling
$SIG{'INT'} = $SIG{'TERM'} = sub {
        print("^C captured\n");
        $TERM=1;
};

# thread
sub stuff_thr($) {
	my ($job)=@_;

	# My thread ID
	my $tid=threads->tid();

	# do some thread stuff
	print "Hi, I am thread: $tid, I need to do something with $job\n";

	# Detach and terminate
	{
		lock($DETACHING);
		threads->detach() if ! threads->is_detached();
	}
	return(0);
}

# main
sub main() {
	# Manage the thread pool until we run out of data or signalled
	# to terminate
	my @jobs=(1..100);
	while (@jobs && ! $TERM) {

		# Keep max threads running
		for (my $needed = $MAX_THREADS - threads->list(); 
			$needed && ! $TERM; $needed--) {

			my $job = shift(@jobs);
			last if (! $job);

			# New thread
			threads->create('stuff_thr',$job);
		}

		# normally fetch a limited amount of data from a db to
		# process, at this point just make sure the job queue
		# is never empty
		if(scalar(@jobs) < 10) {
			@jobs=(1..100);
		}
	}

	while ((threads->list() > 0)) {
		# waiting for threads to finish
		sleep(1);
	}
}

# enter main()
main();