Timer::add(1, "\\Workerman\\Worker::checkIfChildRunning");

/**
* check if child processes is really running
*/
public static function checkIfChildRunning()
{
    foreach (static::$_pidMap as $worker_id => $worker_pid_array) {
    foreach ($worker_pid_array as $pid => $worker_pid) {
        if (!\posix_kill($pid, 0)) {
        unset(static::$_pidMap[$worker_id][$pid]);
        }
    }
  }
}

 $pid = \pcntl_wait($status, \WUNTRACED);
 // Calls x handlers for pending signals again.
 \pcntl_signal_dispatch();
  if($pid > 0)
  {
    // ....
        // Clear process data.
        unset(static::$_pidMap[$worker_id][$pid]);
    // ....
  }

主進程，檢查子進程是否全部退出，然后清理子進程殘留數(shù)據(jù)。這里通過添加定時器去檢測是否運行，子進程退出后，主進程的pcntl_wait 不是會收到退出pid 然后進行清理。
那么為什么還要額外添加定時器去清理呢？這個定時器在主進程退出的時候也沒有進行Timer::del($timer_id) 呢？？？