use warnings;
use strict;

use threads;
use threads::shared;

my $var =1;
share $var;
my $data;
share $data;

my @threads;

push @threads, threads->create(\&thread);
push @threads, threads->create(\&tk_thread);

$_ -> join for @threads;

print "threads joined\n";


sub thread{
    my $counter = 0;
    while (1){
        if ($var==1){
            print "thread doing work\n";
            {
                lock $data;
                $data = $counter++;
            }
            sleep (1);
        }elsif($var == 0){
            print "thread waiting\n";
            sleep(1);
        }else{
            print "thread finished\n";
            return;
        }
    }
}
sub tk_thread{
    require Tk;
    Tk->import;
    my $mw = tkinit();
    my $text = $mw->Text->pack;
    $mw->Button(-text => 'start_stop',
                -command => sub {{lock $var;
                                  $var = $var? 0 : 1
                                  }
                             },
            )->pack;
    $mw->Button(-text => 'beenden',
                -command => sub{{lock $var;
                                 $var = -1;
                                 $mw->destroy;}
                            },
                )->pack;
$mw->repeat(100,sub{{lock $data;
                     $text->insert('end', $data."\n") if $data;
                     $data = '';
                     }
                } );
MainLoop();
}