Hi,

Thank you for the hint with the example of zentara. And thank you for the advice to use Gtk.

I like Tk very much and yesterday arrived the book "Mastering Perl/Tk". So I'd like to stay with Tk at the moment. I nearly finished an application with Tk now and I only need this small thread thing to complete.

Now I could create a solution. Here is the code what is doing what I want.

#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;

my $work:shared = 0;
my $die:shared = 0;

#create thread before any tk code is called
my $thr = threads->create( \&worker );

use Tk;

my $mw = MainWindow->new();
$mw->protocol('WM_DELETE_WINDOW' => sub { &clean_exit }); 

my $button_stop = $mw->Button(-text => 'Stop thread',
                              -command =>
                              sub
                              {                          
                                  $work = 0;
                              })->pack();

my $button_start = $mw->Button(-text => '(Re)Start thread',
                               -command =>
                               sub
                               {
                                   $work = 0;
                                   sleep(1);
                                   $work = 1;
                               })->pack();

MainLoop;

sub clean_exit
{
    my @running_threads = threads->list;
    if (scalar(@running_threads) > 1)
    {
        print "ERROR: Too many threads are active. This was not planne
+d!\n";
    }
    elsif (scalar(@running_threads) == 1)
    {
        $work = 0;
        $die = 1;
        $thr->join;
        exit;
    }
    else
    {
        print "ERROR: There should be at least one thread started!\n";
    }
}

# no Tk code in thread
sub worker
{
    my $i;

  THREAD_START:    
    while($work == 0)
    {
        # just wait
        if( $die == 1 )
        {
            return;
        }            
    }

    $i = 0;
    while($work == 1)
    {
        print $i . "\n";        
        $i++;
    }

    if( $die == 0 )
    {
        goto THREAD_START;
    }
}
[download]

Hopefully you monks can tell me how to improve this code. Using goto is bad and waiting for an event in a loop is also not the best style and costs a lot of performance. But I don't know how to solve it in a different way.

Greetings

Dirk

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