protected function loadPids() : void
    {
        foreach ($this->poolsConfig as $pool => $poolConfig) {
            $pidFiles = glob($this->runPath . '/' . $pool . '/*.pid');
            foreach ($pidFiles as $pidFile) {
                $workerId = basename($pidFile, '.pid');
                $pid = file_get_contents($pidFile);
                if ($this->pidIsValid($pid, $workerId)) {
                    $this->pids[$pool][$workerId] = $pid;
                } else {
                    $this->removePidFile($pidFile);
                }
            }
        }
    }