python 通过发信号的方式杀死父进程,子进程仍然在运行,如何解决？

Question

a文件

import multiprocessingimport osimport signalimport timedef process1():    while True:        print("子进程运行中")        time.sleep(1)# 定义信号处理函数def handle_signal(signum, frame):    print(signum)    if signum == signal.SIGTERM:        print("Received SIGTERM signal. Deleting PID file...")        try:            os.remove("/var/run/crawler.pid")            print("PID file deleted successfully.")        except Exception as e:            print("Error deleting PID file:", e)# 注册信号处理函数signal.signal(signal.SIGTERM, handle_signal)if "__main__" == __name__:    a = multiprocessing.Process(target=process1)    a.daemon = True    a.start()    child_pid = a.pid    parent_pid = os.getpid()    with open("/var/run/crawler.pid", 'w') as f:        f.write(str(parent_pid))    a.join()    print("父进程pid:", parent_pid)    print("子进程pid", child_pid)    # os.waitpid(child_pid, 0)

b文件

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

Answer 1

1. 改用 os.getpgid 来获取主进程和子进程的进程组id 来储存

这里说明一下，据wiki了解到的资料信息，进程组是主进程和子进程组成的一个集合。

In a POSIX-conformant operating system, a process group denotes a collection of one or more processes.Among other things, a process group is used to control the distribution of a signal; when a signal is directed to a process group, the signal is delivered to each process that is a member of the group.

进程组的作用就是用来控制信号的分配到它的所有成员。所以你要杀掉主进程和相应的子进程，就要用 os.killpg 去向这个进程组去发送kill信号，否则常规的 os.kill 只能杀死单进程，而无法将信号量传递到子进程中，还需要你单独手动清除子进程。

2. 将信号注册放在main里面创建子进程后

# a.pyimport multiprocessingimport osimport signalimport timedef process1():    while True:        print("子进程运行中")        time.sleep(1)# 定义信号处理函数def handle_signal(signum, frame):    print(signum)    if signum == signal.SIGTERM:        print("Received SIGTERM signal. Deleting PID file...")        try:            if os.path.exists("./crawler.pid"):                os.remove("./crawler.pid")                print("PID file deleted successfully.")        except Exception as e:            print("Error deleting PID file:", e)# 注册信号处理函数if "__main__" == __name__:    a = multiprocessing.Process(target=process1)    a.daemon = True    a.start()    child_pid = a.pid    parent_pid = os.getpid()    parent_pid_group = os.getpgid(parent_pid)    # 这里更改为进程组id    signal.signal(signal.SIGTERM, handle_signal)    # 从外面放入到main里面    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)    # os.waitpid(child_pid, 0)

同样对另外一个文件修改:

# b.pyimport osimport signalwith open("./crawler.pid", "r") as f:    try:        pid = int(f.read())        os.killpg(pid, signal.SIGTERM)    # 这里换成killpg去执行操作        print("Signal sent successfully to process", pid)    except Exception as e:        print("Error sending signal:", e)