protected function adjustRunningWorkers() : void
    {
        foreach ($this->poolsConfig as $pool => $workerConfig) {
            $workersActive = count($this->pids[$pool]);
            $workersTarget = (int)$workerConfig['instances'];
            if ($workersActive >= $workersTarget) {
                continue;
            }

            $workerDiff = $workersTarget - $workersActive;
            for ($i = 0; $i < $workerDiff; $i++) {
                $this->startupWorker($pool);
            }
        }
    }