use strict;
use warnings;
use POE;

sub handler_start {
   my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
   print "Session ",$session->ID," has started\n";
   $heap->{count} = 0;
   $kernel->yield('increment') if $heap->{count} < 10;
}

sub handler_increment {
   my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
   print "Session ",$session->ID," counted to ",++$heap->{count},".\n"
+;
}

sub handler_stop {
   my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
   print "Session ",$session->ID," has stopped.\n";
}

for (1..10) {
   POE::Session->create(
      inline_states => {
         _start =>    \&handler_start,
         increment => \&handler_increment,
         _stop =>     \&handler_stop,
      },
   );
}

POE::Kernel->run();
[download]

Here's the output...

Session 2 has started
Session 3 has started
Session 4 has started
Session 5 has started
Session 6 has started
Session 7 has started
Session 8 has started
Session 9 has started
Session 10 has started
Session 11 has started
Session 2 counted to 1.
Session 2 has stopped.
Session 3 counted to 1.
Session 3 has stopped.
Session 4 counted to 1.
Session 4 has stopped.
Session 5 counted to 1.
Session 5 has stopped.
Session 6 counted to 1.
Session 6 has stopped.
Session 7 counted to 1.
Session 7 has stopped.
Session 8 counted to 1.
Session 8 has stopped.
Session 9 counted to 1.
Session 9 has stopped.
Session 10 counted to 1.
Session 10 has stopped.
Session 11 counted to 1.
Session 11 has stopped.
[download]

My question is basically, "what is this code trying to accomplish?"

I'm not understanding the point of the $heap->{count} variable.

It seems to always be 1.

Can anyone help me to understand?