#! perl -slw
use strict;
use Carp;
use threads;
use threads::shared;

$| = 1;

our $N    ||= 2;
our $SIZE ||= 1e6;

my $semaphore :shared = 0;
my $running : shared = 0;

'abc' =~ m[b] and print "$`:$&:$'"; ## Use ampersand.

my $bigString = 'ACTG' x $SIZE;
for ( 1 .. $N ) {
    async {
        printf "Thread %s starting\n", threads->tid;
        ++$running;
        my $count = 0;
        while( $bigString =~ m[ACTG]g ) {
            #lock $semaphore;
            #print threads->tid, ' : ', pos( $bigString );
            ++$count;
        }
        --$running;
        printf "Thread %s stopping ($count)\n", threads->tid;
    };
}

Win32::Sleep 100 until $running;
Win32::Sleep 100 while $running;