/**
  * {@inheritdoc}
  */
 protected function execute(InputInterface $input, OutputInterface $output)
 {
     if (isset($this->workerID)) {
         $this->runWorker();
         return $this->getCliReturnCode();
     } else {
         if ($this->processCount > 1) {
             $this->runParallel($input, $output);
             return $this->getCliReturnCode();
         } else {
             return parent::execute($input, $output);
         }
     }
 }