PyQt：带有QRunnables的QThreadPool需要时间退出

Question

我是一个创建QRunnables并在QThreadPool实例中启动它们的类。

我的线程运行良好，但是如果用户想要退出应用程序，应用程序需要很长时间才能停止。当然，由于发起的请求需要时间。

以下是我如何使用QThreadPool，QRunnables的代码段：

import sys
from PyQt5.Qt import QThreadPool, QApplication, QWidget, QVBoxLayout
from PyQt5.Qt import QTimer, QObject, QPushButton, QLabel
from PyQt5.Qt import QRunnable


class BackendQRunnable(QRunnable):
    """
        Class who create a QThread to trigger requests
    """

    def __init__(self, task):
        super(BackendQRunnable, self).__init__()
        self.task = task

    def run(self):
        """
        Run the QRunnable. Trigger actions depending on the selected task

        """

        # Here I make long requests
        if 'user' in self.task:
            self.query_user_data()
        elif 'host' in self.task:
            self.query_hosts_data()
        elif 'service' in self.task:
            self.query_services_data()
        elif 'alignakdaemon' in self.task:
            self.query_daemons_data()
        elif 'livesynthesis' in self.task:
            self.query_livesynthesis_data()
        elif 'history' in self.task:
            self.query_history_data()
        elif 'notifications' in self.task:
            self.query_notifications_data()
        else:
            pass

    @staticmethod
    def query_user_data():
        """
        Launch request for "user" endpoint

        """

        print('Query user data')

    @staticmethod
    def query_hosts_data():
        """
        Launch request for "host" endpoint

        """

        print('Query hosts')

    @staticmethod
    def query_services_data():
        """
        Launch request for "service" endpoint

        """

        print("Query services")

    @staticmethod
    def query_daemons_data():
        """
        Launch request for "alignakdaemon" endpoint

        """

        print('Query daemons')

    @staticmethod
    def query_livesynthesis_data():
        """
        Launch request for "livesynthesis" endpoint

        """

        print('query livesynthesis')

    @staticmethod
    def query_history_data():
        """
        Launch request for "history" endpoint but only for hosts in "data_manager"

        """

        print('Query history')

    @staticmethod
    def query_notifications_data():
        """
        Launch request for "history" endpoint but only for notifications of current user

        """

        print('Query notifications')


class ThreadManager(QObject):
    """
        Class who create BackendQRunnable to periodically request on a Backend
    """

    def __init__(self, parent=None):
        super(ThreadManager, self).__init__(parent)
        self.backend_thread = BackendQRunnable(self)
        self.pool = QThreadPool.globalInstance()
        self.tasks = self.get_tasks()

    def start(self):
        """
        Start ThreadManager

        """

        print("Start backend Manager...")

        # Make a first request
        self.create_tasks()

        # Then request periodically
        timer = QTimer(self)
        timer.setInterval(10000)
        timer.start()
        timer.timeout.connect(self.create_tasks)

    @staticmethod
    def get_tasks():
        """
        Return the tasks to run in BackendQRunnable

        :return: tasks to run
        :rtype: list
        """

        return [
            'notifications', 'livesynthesis', 'alignakdaemon', 'history', 'service', 'host', 'user',
        ]

    def create_tasks(self):
        """
        Create tasks to run

        """

        for cur_task in self.tasks:
            backend_thread = BackendQRunnable(cur_task)

            # Add task to QThreadPool
            self.pool.start(backend_thread)

    def exit_pool(self):
        """
        Exit all BackendQRunnables and delete QThreadPool

        """

        # When trying to quit, the application takes a long time to stop
        self.pool.globalInstance().waitForDone()
        self.pool.deleteLater()

        sys.exit(0)


if __name__ == '__main__':
    app = QApplication(sys.argv)

    thread_manager = ThreadManager()
    thread_manager.start()

    layout = QVBoxLayout()

    label = QLabel("Start")
    button = QPushButton("DANGER!")
    button.pressed.connect(thread_manager.exit_pool)

    layout.addWidget(label)
    layout.addWidget(button)

    w = QWidget()

    w.setLayout(layout)
    w.show()

    sys.exit(app.exec_())

在函数exit_pool中，我等到线程完成并删除QThreadPool实例...

有没有办法不等待每个线程直接停止一切？

编辑解决方案：

所以我以不同的方式接触过这个主题。我用QRunnable替换了我的QThread。我删除了QThreadPool，我自己在列表中管理线程。我还添加了pyqtSignal以停止QTimer并通过quit()函数关闭正在运行的线程。

就像我所有的线程都没有问题一样退出。

import sys
from PyQt5.Qt import QThread, QApplication, QWidget, QVBoxLayout
from PyQt5.Qt import QTimer, QObject, QPushButton, QLabel, pyqtSignal


class BackendQThread(QThread):
    """
        Class who create a QThread to trigger requests
    """

    quit_thread = pyqtSignal(name='close_thread')

    def __init__(self, task):
        super(BackendQThread, self).__init__()
        self.task = task

    def run(self):
        """
        Run the actions depending on the selected task

        """

        # Here I make long requests
        if 'user' in self.task:
            self.query_user_data()
        elif 'host' in self.task:
            self.query_hosts_data()
        elif 'service' in self.task:
            self.query_services_data()
        elif 'alignakdaemon' in self.task:
            self.query_daemons_data()
        elif 'livesynthesis' in self.task:
            self.query_livesynthesis_data()
        elif 'history' in self.task:
            self.query_history_data()
        elif 'notifications' in self.task:
            self.query_notifications_data()
        else:
            pass

    @staticmethod
    def query_user_data():
        """
        Launch request for "user" endpoint

        """

        print('Query user data')

    @staticmethod
    def query_hosts_data():
        """
        Launch request for "host" endpoint

        """

        print('Query hosts')

    @staticmethod
    def query_services_data():
        """
        Launch request for "service" endpoint

        """

        print("Query services")

    @staticmethod
    def query_daemons_data():
        """
        Launch request for "alignakdaemon" endpoint

        """

        print('Query daemons')

    @staticmethod
    def query_livesynthesis_data():
        """
        Launch request for "livesynthesis" endpoint

        """

        print('query livesynthesis')

    @staticmethod
    def query_history_data():
        """
        Launch request for "history" endpoint but only for hosts in "data_manager"

        """

        print('Query history')

    @staticmethod
    def query_notifications_data():
        """
        Launch request for "history" endpoint but only for notifications of current user

        """

        print('Query notifications')


class ThreadManager(QObject):
    """
        Class who create BackendQThread to periodically request on a Backend
    """

    def __init__(self, parent=None):
        super(ThreadManager, self).__init__(parent)
        self.tasks = self.get_tasks()
        self.timer = QTimer()
        self.threads = []

    def start(self):
        """
        Start ThreadManager

        """

        print("Start backend Manager...")

        # Make a first request
        self.create_tasks()

        # Then request periodically
        self.timer.setInterval(10000)
        self.timer.start()
        self.timer.timeout.connect(self.create_tasks)

    @staticmethod
    def get_tasks():
        """
        Return the available tasks to run

        :return: tasks to run
        :rtype: list
        """

        return [
            'notifications', 'livesynthesis', 'alignakdaemon', 'history', 'service', 'host', 'user',
        ]

    def create_tasks(self):
        """
        Create tasks to run

        """

        # Here I reset the list of threads
        self.threads = []
        for cur_task in self.tasks:
            backend_thread = BackendQThread(cur_task)

            # Add task to QThreadPool
            backend_thread.start()
            self.threads.append(backend_thread)

    def stop(self):
        """
        Stop the manager and close all QThreads

        """

        print("Stop tasks")
        self.timer.stop()
        for task in self.threads:
            task.quit_thread.emit()

        print("Tasks finished")


if __name__ == '__main__':
    app = QApplication(sys.argv)

    layout = QVBoxLayout()
    widget = QWidget()
    widget.setLayout(layout)

    thread_manager = ThreadManager()

    start_btn = QPushButton("Start")
    start_btn.clicked.connect(thread_manager.start)
    layout.addWidget(start_btn)

    stop_btn = QPushButton("Stop")
    stop_btn.clicked.connect(thread_manager.stop)
    layout.addWidget(stop_btn)

    widget.show()

    sys.exit(app.exec_())

Answer 1

一旦启动QRunnable，您就无法停止。但是，您可以采取一些简单的方法来缩短示例中的等待时间。

首先，您可以停止计时器，以便它不会再添加任务。其次，您可以clear the thread-pool以便删除任何待处理的任务。第三，你可以尝试setting a smaller maximum thread count看看它是否仍能达到可接受的性能。默认情况下，线程池将使用QThread.idealThreadCount()来设置最大线程数 - 这通常意味着系统上每个处理器核心都有一个。

最后一个选项是提供一种中断在runnables中执行的代码的方法。如果代码运行一个循环，可以定期检查一个标志以查看它是否应该继续，那么这才真正可行。在您的示例中，看起来您可以为标志使用单个共享类属性，因为所有任务都调用静态方法。但是如果代码不能以这种方式中断，那么你就无法做其他事情了 - 你只需要等待当前正在运行的任务完成。