Python Thead.join（）仅在所有线程完成后才帮助打印字符串

我目前正在尝试编写一个函数，该函数实现以下功能：

• 以随机顺序从“消息”列表中获取所有消息，同时确保没有任何消息重复
• 在1-10秒范围内的随机延迟秒数后打印
• 所有线程完成后，它将打印一个字符串“打印完成。您将在5秒钟后返回主菜单。”

然而，我遇到的问题是字符串“Printing is finished…”打印在随机消息之间，而不是在它们之后

我的困惑源于这样一个事实，即.join（）方法完全适用于类似的函数。只有在所有线程完成后，才会打印字符串。它们之间的主要区别在于另一个函数不接受任何随机输入。相反，它迭代一个名为“messages_和_times”的全局字典，其中key:value对来自用户输入的消息和秒数（用户输入由另一个函数处理）

下面可以看到函数选项_3（），它不起作用，函数选项_2（）起作用。在最底层，我将包含整个代码以供进一步参考

有人能帮我理解我做错了什么吗

提前感谢您的时间和帮助

附言。

clear（）

功能用于在每次输入后清除终端显示

非工作功能：

def option_3():
    clear()
    messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                "message_6", "message_7", "message_8", "message_9", "message_10"]

    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message in messages:
        randomized_messages = []
        random_index = random.randint(0, len(messages) - 1)
        randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

def option_2():
    global messages_and_times

    clear()
    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message, seconds in messages_and_times.items():
        t = Thread(target=threading_function, args=(message, seconds))
        t.start()

    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

import os
import random
clear = lambda: os.system('cls')

messages_and_times = {}


def main_menu():

    def option_1():
        global messages_and_times

        clear()
        message = input(
            "Please type in a message you would like to add to the list:")
        clear()
        seconds = int(
            input("Please type in the time of delay for this message:"))
        messages_and_times[message] = seconds

        def create_dictionary():

            clear()
            answer = input(
                "Would you like to add another message? (yes/no)").lower()
            if answer == "yes":
                option_1()
            elif answer == "no":
                clear()
                print("You will now be returned to the main menu.")
                time.sleep(1.5)
                main_menu()
            else:
                clear()
                print("Please answer yes or no.")
                time.sleep(1.5)
                create_dictionary()
        create_dictionary()

    def option_2():
        global messages_and_times

        clear()
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message, seconds in messages_and_times.items():
            t = Thread(target=threading_function, args=(message, seconds))
            t.start()

        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()

    def option_3():
        clear()
        messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                    "message_6", "message_7", "message_8", "message_9", "message_10"]
        randomized_messages = []
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message in messages:
            random_index = random.randint(0, len(messages) - 1)
            randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()


    clear()
    selection = 0
    while selection == 0:
        print(("-" * 15) + "MAIN MENU" + ("-" * 15) + "\n")
        print("1: Input a message and a corresponding time of delay before its display.")
        print("2: Print your customized list of messages.")
        print("3: Print random messages with random delays.\n")

        selection = int(input(
            "Please select one of the options, by typing in the corresponding number:"))

        if selection == 1:
            option_1()
        elif selection == 2:
            option_2()
        elif selection == 3:
            option_3()
        else:
            clear()
            print("Please select from options 1 - 3.\n")
            time.sleep(1.5)
            main_menu()

---

工作职能：

def option_3():
    clear()
    messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                "message_6", "message_7", "message_8", "message_9", "message_10"]

    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message in messages:
        randomized_messages = []
        random_index = random.randint(0, len(messages) - 1)
        randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

def option_2():
    global messages_and_times

    clear()
    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message, seconds in messages_and_times.items():
        t = Thread(target=threading_function, args=(message, seconds))
        t.start()

    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

import os
import random
clear = lambda: os.system('cls')

messages_and_times = {}


def main_menu():

    def option_1():
        global messages_and_times

        clear()
        message = input(
            "Please type in a message you would like to add to the list:")
        clear()
        seconds = int(
            input("Please type in the time of delay for this message:"))
        messages_and_times[message] = seconds

        def create_dictionary():

            clear()
            answer = input(
                "Would you like to add another message? (yes/no)").lower()
            if answer == "yes":
                option_1()
            elif answer == "no":
                clear()
                print("You will now be returned to the main menu.")
                time.sleep(1.5)
                main_menu()
            else:
                clear()
                print("Please answer yes or no.")
                time.sleep(1.5)
                create_dictionary()
        create_dictionary()

    def option_2():
        global messages_and_times

        clear()
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message, seconds in messages_and_times.items():
            t = Thread(target=threading_function, args=(message, seconds))
            t.start()

        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()

    def option_3():
        clear()
        messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                    "message_6", "message_7", "message_8", "message_9", "message_10"]
        randomized_messages = []
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message in messages:
            random_index = random.randint(0, len(messages) - 1)
            randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()


    clear()
    selection = 0
    while selection == 0:
        print(("-" * 15) + "MAIN MENU" + ("-" * 15) + "\n")
        print("1: Input a message and a corresponding time of delay before its display.")
        print("2: Print your customized list of messages.")
        print("3: Print random messages with random delays.\n")

        selection = int(input(
            "Please select one of the options, by typing in the corresponding number:"))

        if selection == 1:
            option_1()
        elif selection == 2:
            option_2()
        elif selection == 3:
            option_3()
        else:
            clear()
            print("Please select from options 1 - 3.\n")
            time.sleep(1.5)
            main_menu()

---

整个主菜单（）函数：

def option_3():
    clear()
    messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                "message_6", "message_7", "message_8", "message_9", "message_10"]

    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message in messages:
        randomized_messages = []
        random_index = random.randint(0, len(messages) - 1)
        randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

def option_2():
    global messages_and_times

    clear()
    print("Printing initialized:\n")

    def threading_function(message, seconds):
        time.sleep(seconds)
        print(message)

    for message, seconds in messages_and_times.items():
        t = Thread(target=threading_function, args=(message, seconds))
        t.start()

    t.join()
    time.sleep(0.5)
    print(
        "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
    time.sleep(5)
    main_menu()

import os
import random
clear = lambda: os.system('cls')

messages_and_times = {}


def main_menu():

    def option_1():
        global messages_and_times

        clear()
        message = input(
            "Please type in a message you would like to add to the list:")
        clear()
        seconds = int(
            input("Please type in the time of delay for this message:"))
        messages_and_times[message] = seconds

        def create_dictionary():

            clear()
            answer = input(
                "Would you like to add another message? (yes/no)").lower()
            if answer == "yes":
                option_1()
            elif answer == "no":
                clear()
                print("You will now be returned to the main menu.")
                time.sleep(1.5)
                main_menu()
            else:
                clear()
                print("Please answer yes or no.")
                time.sleep(1.5)
                create_dictionary()
        create_dictionary()

    def option_2():
        global messages_and_times

        clear()
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message, seconds in messages_and_times.items():
            t = Thread(target=threading_function, args=(message, seconds))
            t.start()

        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()

    def option_3():
        clear()
        messages = ["message_1", "message_2", "message_3", "message_4", "message_5",
                    "message_6", "message_7", "message_8", "message_9", "message_10"]
        randomized_messages = []
        print("Printing initialized:\n")

        def threading_function(message, seconds):
            time.sleep(seconds)
            print(message)

        for message in messages:
            random_index = random.randint(0, len(messages) - 1)
            randomized_messages.append(messages.pop(random_index))
        for msg in randomized_messages:
            t = Thread(target=threading_function, args=(msg, random.choice(range(1,11))))
            t.start()


        t.join()
        time.sleep(0.5)
        print(
            "\nPrinting is finished. You will be returned to the main menu in 5 seconds.")
        time.sleep(5)
        main_menu()


    clear()
    selection = 0
    while selection == 0:
        print(("-" * 15) + "MAIN MENU" + ("-" * 15) + "\n")
        print("1: Input a message and a corresponding time of delay before its display.")
        print("2: Print your customized list of messages.")
        print("3: Print random messages with random delays.\n")

        selection = int(input(
            "Please select one of the options, by typing in the corresponding number:"))

        if selection == 1:
            option_1()
        elif selection == 2:
            option_2()
        elif selection == 3:
            option_3()
        else:
            clear()
            print("Please select from options 1 - 3.\n")
            time.sleep(1.5)
            main_menu()

编辑（供将来参考的最终解决方案）：

多亏了Almog David的建议，以下是我如何修改函数以使其按预期工作的。我希望这有助于将来有人浏览解决方案

选项2（）：

选项3（）：

---

问题是，您只等待最后一个线程加入（因为循环结束时't'变量保存最后创建的线程对象），所以当最后一个线程完成并且程序继续时，加入函数返回

即使在选项2上，我也能够通过提供以下信息再现此错误：

messages_and_times = {"message_0": 3,
                  "message_1": 3,
                  "message_2": 1}

上述配置的结果是：

message_2

Printing is finished. You will be returned to the main menu in 5 seconds.
message_0
message_1

您应该做什么来修复它：

threads = []

for message, seconds in messages_and_times.items():
    t = Thread(target=threading_function, args=(message, seconds))
    t.start()
    threads.append(t)

for t in threads:
    t.join()

---

在非工作版本中，您有一个

t.join（）

，它跟在两个嵌套的

for

循环之后，循环的最内部有一个

t=Thread（…）

，因此执行

join（）

时

t的值是分配给它的最后一个线程。这就是你想要的吗？啊，非常感谢。我还注意到我犯的另一个错误。如果我使用.pop（）方法，“消息”列表最终只剩下5个条目，“随机化消息”列表也是如此。我将编辑我的原始帖子以包含最终解决方案。是的，你是对的，我也注意到了这种行为，但我认为这是故意的。