protected function cleanManagerSet()
    {
        foreach ($this->managerSet as $managerKey => $manager) {

            /** @var $manager \Thread */
            if (!$manager->isRunning()) {
                $this->getLogger()->debug("Daemon clean old manager : {$managerKey}", [__NAMESPACE__]);
                unset($this->managerSet[$managerKey]);
            }
        }

        return $this;
    }