python - 停止线程 - 获取无效的线程 ID

Question

这个问题之前已经被回答过，我正在尝试在 first answer outlined here 中实现第二个解决方案。 (注意:第一个解决方案与我无关，我的线程正在从外部库运行服务器，并且无法修改以检查标志)

我尝试实现符合我的情况的最简单的情况。我有一个生成线程的类，并且该线程应该在外部停止(该线程永远不会自然完成，如本例所示)。 注意:_async_raise 和 ThreadWithExc 是此问题的已接受答案的复制/粘贴:

import threading
import inspect
import ctypes
import time

# https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread-in-python
def _async_raise(tid, exctype):
    if not inspect.isclass(exctype):
        raise TypeError("Only types can be raised (not instances)")
    res = ctypes.pythonapi.PyThreadState_SetAsyncExc(tid,
                                                  ctypes.py_object(exctype))
    if res == 0:
        raise ValueError("invalid thread id")
    elif res != 1:
        ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, 0)
        raise SystemError("PyThreadState_SetAsyncExc failed")

# https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread-in-python
class ThreadWithExc(threading.Thread):
    def _get_my_tid(self):

        if not self.isAlive():
            raise threading.ThreadError("the thread is not active")

        if hasattr(self, "_thread_id"):
            return self._thread_id

        for tid, tobj in threading._active.items():
            if tobj is self:
                self._thread_id = tid
                return tid

        raise AssertionError("could not determine the thread's id")

    def raiseExc(self, exctype):
        _async_raise( self._get_my_tid(), exctype )

def work():
    while True:
        print('work')
        time.sleep(1)

class Server:
    def __init__(self):
        self.thread = ThreadWithExc(target=work)

    def start(self):
        self.thread.start()

    def stop(self):
        _async_raise(self.thread.raiseExc(TypeError))


server = Server()
server.start()
server.stop()

这会产生 ValueError: invalid thread id 异常。我还尝试了 threading.get_ident() 而不是答案的 _get_my_tid();这给了我另一个 ID，但那个 ID 也是无效的。

Answer 1

我认为您遇到的根本问题是您没有正确调用 _async_raise() ，应该替换该行:

_async_raise(self.thread.raiseExc(TypeError))

在Server.stop()中:

self.thread.raiseExc(TypeError)

但是，如果您这样做，您将在线程 Thread-1 中得到一个异常:，因为 work() 函数中没有异常处理程序来处理由 raiseExc() 引发的异常。

以下内容修复了该问题并使用自定义 Exception 子类使事情变得更加清晰:

import threading
import inspect
import ctypes
import time

# https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread-in-python
def _async_raise(tid, exctype):
    if not inspect.isclass(exctype):
        raise TypeError("Only types can be raised (not instances)")
    res = ctypes.pythonapi.PyThreadState_SetAsyncExc(tid,
                                                  ctypes.py_object(exctype))
    if res == 0:
        raise ValueError("invalid thread id")
    elif res != 1:
        ctypes.pythonapi.PyThreadState_SetAsyncExc(tid, 0)
        raise SystemError("PyThreadState_SetAsyncExc failed")

# https://stackoverflow.com/questions/323972/is-there-any-way-to-kill-a-thread-in-python
class ThreadWithExc(threading.Thread):
    def _get_my_tid(self):

        if not self.isAlive():
            raise threading.ThreadError("the thread is not active")

        if hasattr(self, "_thread_id"):
            return self._thread_id

        for tid, tobj in threading._active.items():
            if tobj is self:
                self._thread_id = tid
                return tid

        raise AssertionError("could not determine the thread's id")

    def raiseExc(self, exctype):
        _async_raise(self._get_my_tid(), exctype )

def work():
    try:
        while True:
            print('work')
            time.sleep(1)
    except Server.ThreadStopped:
        pass

    print('exiting work() function')

class Server:
    class ThreadStopped(Exception): pass

    def __init__(self):
        self.thread = ThreadWithExc(target=work)

    def start(self):
        self.thread.start()

    def stop(self):
#        _async_raise(self.thread.raiseExc(TypeError))
        self.thread.raiseExc(self.ThreadStopped)

server = Server()
server.start()
server.stop()

输出:

work
exiting work() function