Tidy up when guests are gone (write cb)

gistfile1.pl

#!/usr/bin/env perl
use Mojolicious::Lite;

get '/' => sub {
  my $c = shift;
  $c->res->headers->content_length(5);
  $c->write(
    'Hallo' => sub {
      my $c = shift;
      sleep(3);
      $c->app->log->debug('finished');
    }
  );
};

app->start