如何从GUI停止QThread

Question

这是我之前发布的前一个问题的后续问题.问题是当使用NOT子类化Qthread的推荐方法时,如何从GUI停止(终止|退出)QThread,而是使用QObject然后将其移动到QThread.下面是一个工作实例.我可以启动GUI和Qthread,我可以让后者更新GUI.但是,我无法阻止它.我为qthread(quit(),exit(),甚至terminate())尝试了几种方法无济于事.非常感谢.

这是完整的代码:

import time, sys
from PyQt4.QtCore  import *
from PyQt4.QtGui import * 

class SimulRunner(QObject):
    'Object managing the simulation'

    stepIncreased = pyqtSignal(int, name = 'stepIncreased')
    def __init__(self):
        super(SimulRunner, self).__init__()
        self._step = 0
        self._isRunning = True
        self._maxSteps = 20

    def longRunning(self):
        while self._step  < self._maxSteps  and self._isRunning == True:
            self._step += 1
            self.stepIncreased.emit(self._step)
            time.sleep(0.1)

    def stop(self):
        self._isRunning = False

class SimulationUi(QDialog):
    'PyQt interface'

    def __init__(self):
        super(SimulationUi, self).__init__()

        self.goButton = QPushButton('Go')
        self.stopButton = QPushButton('Stop')
        self.currentStep = QSpinBox()

        self.layout = QHBoxLayout()
        self.layout.addWidget(self.goButton)
        self.layout.addWidget(self.stopButton)
        self.layout.addWidget(self.currentStep)
        self.setLayout(self.layout)

        self.simulRunner = SimulRunner()
        self.simulThread = QThread()
        self.simulRunner.moveToThread(self.simulThread)
        self.simulRunner.stepIncreased.connect(self.currentStep.setValue)


        self.stopButton.clicked.connect(simulThread.qui)  # also tried exit() and terminate()
        # also tried the following (didn't work)
        # self.stopButton.clicked.connect(self.simulRunner.stop)
        self.goButton.clicked.connect(self.simulThread.start)
        self.simulThread.started.connect(self.simulRunner.longRunning)
        self.simulRunner.stepIncreased.connect(self.current.step.setValue)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    simul = SimulationUi()
    simul.show()
    sys.exit(app.exec_())

Answer 1

我很久以前就知道了,但我偶然发现了同样的问题.

我一直在寻找一种合适的方法来做到这一点.最后很容易.退出应用程序时,需要停止任务,并且需要停止调用其退出方法的线程.请参见底部的stop_thread方法.你需要等待线程完成.否则你将得到QThread:当线程仍然在退出时运行'消息时被销毁.

(我也改变了我的代码使用pyside)

import time, sys
from PySide.QtCore  import *
from PySide.QtGui import *

class Worker(QObject):
    'Object managing the simulation'

    stepIncreased = Signal(int)

    def __init__(self):
        super(Worker, self).__init__()
        self._step = 0
        self._isRunning = True
        self._maxSteps = 20

    def task(self):
        if not self._isRunning:
            self._isRunning = True
            self._step = 0

        while self._step  < self._maxSteps  and self._isRunning == True:
            self._step += 1
            self.stepIncreased.emit(self._step)
            time.sleep(0.1)

        print "finished..."

    def stop(self):
        self._isRunning = False


class SimulationUi(QDialog):
    def __init__(self):
        super(SimulationUi, self).__init__()

        self.btnStart = QPushButton('Start')
        self.btnStop = QPushButton('Stop')
        self.currentStep = QSpinBox()

        self.layout = QHBoxLayout()
        self.layout.addWidget(self.btnStart)
        self.layout.addWidget(self.btnStop)
        self.layout.addWidget(self.currentStep)
        self.setLayout(self.layout)

        self.thread = QThread()
        self.thread.start()

        self.worker = Worker()
        self.worker.moveToThread(self.thread)
        self.worker.stepIncreased.connect(self.currentStep.setValue)

        self.btnStop.clicked.connect(lambda: self.worker.stop())
        self.btnStart.clicked.connect(self.worker.task)

        self.finished.connect(self.stop_thread)

    def stop_thread(self):
        self.worker.stop()
        self.thread.quit()
        self.thread.wait()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    simul = SimulationUi()
    simul.show()
    sys.exit(app.exec_())

Answer 2

我发现我原来的问题实际上是两个问题合二为一：为了停止主线程的辅助线程，你需要两件事：

1. 能够从主线程向下通信到辅助线程

2. 发送适当的信号来停止线程

我无法解决（2），但我想出了如何解决（1），这为我原来的问题提供了解决方法。我可以停止线程的处理（方法longRunning()） ，而不是停止线程

问题是辅助线程只有运行自己的事件循环才能响应信号。常规的 Qthread（这是我的代码使用的）则不然。不过，将 QThread 子类化以达到这种效果是很容易的：

class MyThread(QThread):
    def run(self):
        self.exec_()

并在我的代码中使用self.simulThread = MyThread()而不是原来的self.simulThread = Qthread(). 这确保辅助线程运行事件循环。但这还不够。该longRunning()方法需要有机会实际处理来自主线程的事件。在这个 SO 答案的帮助下，我发现QApplication.processEvent()在longRunning()方法中简单添加 a 给了辅助线程这样的机会。我现在可以停止在辅助线程中执行的处理，即使我还没有弄清楚如何停止线程本身。

总结一下。我的 longRunning 方法现在如下所示：

def longRunning(self):
    while self._step  < self._maxSteps  and self._isRunning == True:
        self._step += 1
        self.stepIncreased.emit(self._step)
        time.sleep(0.1)
        QApplication.processEvents() 

我的 GUI 线程有以下三行来完成这项工作（除了上面列出的 QThread 子类之外）：

    self.simulThread = MyThread()
    self.simulRunner.moveToThread(self.simulThread)
    self.stopButton.clicked.connect(self.simulRunner.stop)

欢迎评论！