如何利用进程组信号优雅地终止父进程及其所有子进程？

import multiprocessingimport osimport signalimport timedef process1():    while true:        print("子进程运行中")        time.sleep(1)if __name__ == "__main__":    a = multiprocessing.process(target=process1)    a.daemon = true    a.start()    child_pid = a.pid    parent_pid = os.getpid()    # 获取并存储进程组id    parent_pid_group = os.getpgid(parent_pid)    # 在创建子进程后注册信号处理函数    signal.signal(signal.sigterm, handle_signal)    with open("crawler.pid", "w") as f:        f.write(str(parent_pid_group))    a.join()    print("父进程pid:", parent_pid)    print("子进程pid:", child_pid)

import osimport signalwith open("crawler.pid", "r") as f:    try:        pid = int(f.read())        os.killpg(pid, signal.SIGTERM)        print("Signal sent successfully to process", pid)    except Exception as e:        print("Error sending signal:", e)