Question

我正在尝试在Python中开始使用多线程。我有多个线程获取锁，执行操作，释放锁，并将结果输出到csv文件。如果主线程完成，则应终止线程（例如，通过按Ctrl + C）。这是怎么做到的？

我认为使线程守护进程应该完成这项工作，因为“当只剩下守护进程线程时，整个Python程序退出”（官方Python文档）。这还不够。根据{{3}}，然后我尝试捕获KeyboardInterrupt，然后手动终止线程。这也不起作用，似乎没有正确捕获KeyboardInterrupt。

这让我觉得，在Python中有一些关于多线程的东西，我误解了......找到附加的代码：

import random import csv import sys from datetime import datetime import threading lock = threading.Lock() def observer(obs): print("In " + str(obs)) sys.stdout.flush() with open("data/test_" + str(obs) + ".csv", 'a', newline='') as csvfile: while True: datenow = datetime.today() lock.acquire() print(str(obs) + "acquired") sum = 0 for i in range(10000): sum = sum + random.random() print(str(obs) + "released") sys.stdout.flush() lock.release() writer = csv.writer(csvfile, delimiter=',', quoting=csv.QUOTE_ALL) writer.writerow([datenow.isoformat(), sum/10000]) #print(str(obs) + ": " + datenow.isoformat() + " " + str(sum/1000)) sys.stdout.flush() if __name__ == "__main__": observe = [1, 2, 3, 4] processes = [] for obs in observe: process = threading.Thread(target=observer, args=(obs,), daemon=True) processes.append(process) print("Start processes") for p in processes: p.start() print("Started") try: for p in processes: p.join() except KeyboardInterrupt: for p in processes: p.terminate() print("Keyboard interrupt") print("Finished")

谢谢！

Answer 1

错误

try:
    for p in processes:
        p.join()
except KeyboardInterrupt:
    for p in processes:
        p.terminate()
    print("Keyboard interrupt")

您的主题永远不会退出while True:循环，因此您将永远加入它们。但那不是重点。

如果没有抓住Ctrl-C（又名KeyboardInterrupt），我最好的选择是：

您正在Windows
运行脚本的shell操纵进程，实际上您从未看到Ctrl-C因为您的程序被突然终止。

你的问题是：

您的程序实际上并不知道它已经终止，这就是线程挂起的原因。

如果上述假设是正确的，请尝试使用此代码（来自Python - Windows - Exiting Child Process when "unrelated" parent dies/crashes）

import sys

def win_wait_for_parent(raise_exceptions=False):
    if not sys.platform == 'win32':
        return True

    # When started under cygwin, the parent process will die leaving a child
    # hanging around. The process has to be waited upon
    import ctypes
    from ctypes.wintypes import DWORD, BOOL, HANDLE
    import os
    import threading

    INFINITE = -1
    SYNCHRONIZE = 0x00100000

    kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)

    kernel32.OpenProcess.argtypes = (DWORD, BOOL, DWORD)
    kernel32.OpenProcess.restype = HANDLE

    kernel32.WaitForSingleObject.argtypes = (HANDLE, DWORD)
    kernel32.WaitForSingleObject.restype = DWORD

    phandle = kernel32.OpenProcess(SYNCHRONIZE, 0, os.getppid())

    def check_parent():
        # Get a token with right access to parent and wait for it to be
        # signaled (die). Exit ourselves then
            kernel32.WaitForSingleObject(phandle, INFINITE)
            os._exit(0)

    if not phandle:
        if raise_exceptions:
            raise ctypes.WinError(ctypes.get_last_error())

        return False

主程序退出时终止线程

1 个答案: