请教下 主进程接到reload信号后 为什么只posix_kill了一个进程id

// Continue reload.
$one_worker_pid = current(self::$_pidsToRestart);     <====只取了需要resetart的进程里的一个
// Send reload signal to a worker process.
posix_kill($one_worker_pid, SIGUSR1);
// If the process does not exit after self::KILL_WORKER_TIMER_TIME seconds try to kill it.
Timer::add(self::KILL_WORKER_TIMER_TIME, 'posix_kill', array($one_worker_pid, SIGKILL), false);