在正在運行的線程中設置變量以停止線程

Question

我有一個對象cooker其run()方法啟動一個新的線程cookingThread 。 5秒鍾后，我怎么能阻止cookingThread通過設置變量stopThread ？

嘗試使用cooker.toggle()首先啟動線程，但是下一個cooker.toggle()無法停止線程。

下面的代碼給我錯誤NameError: global name 'cookingThread' is not defined

import threading
import time

class Cooker(object):

    def __init__(self, recipe):
        self.active = False
        self.recipe = recipe

    def toggle(self):
        if not self.active:
            self.active = True
            self.run()

        else:
            self.active = False
            # How can this stop flag be passed into the running thread?
            cookingThread.stopThread = True


    def run(self):
        cookingThread = CookingThread(self.recipe)
        cookingThread.start()

CookingThread

class CookingThread(threading.Thread):

    def __init__(self, recipe):
        super(CookingThread, self).__init__()
        self.recipe = recipe
        self.stopThread = False

    def run(self):
        for i in range(self.recipe):
            # Check if we should stop the thread
            if self.stopThread:
                return
            else:
                print 'Cooking...'
                time.sleep(1)

主要

cooker = Cooker(10)
cooker.toggle()    # Starts the thread

time.sleep(5)
cooker.toggle()    # Stops the thread (does not work)

Answer 1

問題是cookingThread是僅在Cooker.run()方法內部作用域的方法。 該錯誤表明您需要將其聲明為全局方法，以便能夠從所有方法進行訪問。 但這不是一個好習慣。

您可以執行以下操作

import threading
import time

class Cooker(object):

    def __init__(self, recipe):
        self.active = False
        self.recipe = recipe

    def toggle(self):
        if not self.active:
            self.active = True
            self.run()

        else:
            self.active = False
            # How can this stop flag be passed into the running thread?
            self.cookingThread.stop()


    def run(self):
        self.cookingThread = CookingThread(self.recipe)
        self.cookingThread.start()

並如下更改CookingThread。

class CookingThread(threading.Thread):

    def __init__(self, recipe):
        super(CookingThread, self).__init__()
        self.recipe = recipe
        self.stopThread = False

    def run(self):
        for i in range(self.recipe):
            # Check if we should stop the thread
            if self.stopThread:
                return
            else:
                print 'Cooking...'
                time.sleep(1)

    def stop(self):
        self.stopThread = True

根據經驗，開發面向對象程序設計時切勿直接訪問字段（例如cookingThread.stopThread 。 嘗試使用諸如stop的方法進行實際修改。