function derefTask(\CharlotteDunois\Phoebe\AsyncTask $task) {
        if(isset($this->refBag[$task->id])) {
            unset($this->refBag[$task->id]);
            
            if(\count($this->refBag) === 0 && $this->stack->count() === 0) {
                $this->bag->lastEmptyStack = \time();
                $this->bag->currentlyBusy = false;
                
                $msg = new \CharlotteDunois\Phoebe\Message('internal-worker-stack-free', null);
                $this->sendMessageToPool($msg);
            }
        }
    }