在python qt5应用程序中线程的正确模式是什么？

Question

我想写一个pyqt5应用程序与长时间运行，但不是CPU密集型过程。我希望能够在不挂上UI的情况下运行它，所以我试图使用线程，但是因为它看起来并不像我可以运行一个线程并在其代码完成后停止，以便它可以再次运行，我已经尝试设置线程以等待变量在运行前更改。

我知道这不能成为在pyqt应用程序中运行长进程的正确模式。

import time 
import threading 
from PyQt5 import QtWidgets, uic 


class MyApp(QtWidgets.QMainWindow): 
    _run_thread = False 

    def __init__(self): 
     QtWidgets.QMainWindow.__init__(self) 
     self.ui = uic.loadUi('myapp.ui', self) 

     self.ui.start_thread_button.clicked.connect(self._run_thread_function) 

     self._thread = threading.Thread(target=self._run_thread_callback) 
     self._thread.daemon = True 
     self._thread.start() 

     self.ui.show() 

    def _run_thread_callback(self): 
     while True: 
      if self._run_thread: 
       print("running thread code...") 
       time.sleep(10) 
       print("thread code finished") 
       self._run_thread = False 

    def _run_thread_function(self): 
     print("starting thread...") 
     self._run_thread = True 


def main(): 
    app = QtWidgets.QApplication(sys.argv) 
    MyApp() 
    sys.exit(app.exec_()) 

if __name__ == '__main__': 
    main() 

Answer 1

下面是显示如何启动和停止工作线程，并安全地与GUI线程comminucate一个简单的演示。

import sys 
from PyQt5 import QtCore, QtWidgets 

class Worker(QtCore.QThread): 
    dataSent = QtCore.pyqtSignal(dict) 

    def __init__(self, parent=None): 
     super(Worker, self).__init__(parent) 
     self._stopped = True 
     self._mutex = QtCore.QMutex() 

    def stop(self): 
     self._mutex.lock() 
     self._stopped = True 
     self._mutex.unlock() 

    def run(self): 
     self._stopped = False 
     for count in range(10): 
      if self._stopped: 
       break 
      self.sleep(1) 
      data = { 
       'message':'running %d [%d]' % (
        count, QtCore.QThread.currentThreadId()), 
       'time': QtCore.QTime.currentTime(), 
       'items': [1, 2, 3], 
       } 
      self.dataSent.emit(data) 

class Window(QtWidgets.QWidget): 
    def __init__(self): 
     super(Window, self).__init__() 
     self.edit = QtWidgets.QPlainTextEdit() 
     self.edit.setReadOnly(True) 
     self.button = QtWidgets.QPushButton('Start') 
     self.button.clicked.connect(self.handleButton) 
     layout = QtWidgets.QVBoxLayout(self) 
     layout.addWidget(self.edit) 
     layout.addWidget(self.button) 
     self._worker = Worker() 
     self._worker.started.connect(self.handleThreadStarted) 
     self._worker.finished.connect(self.handleThreadFinished) 
     self._worker.dataSent.connect(self.handleDataSent) 

    def handleThreadStarted(self): 
     self.edit.clear() 
     self.button.setText('Stop') 
     self.edit.appendPlainText('started') 

    def handleThreadFinished(self): 
     self.button.setText('Start') 
     self.edit.appendPlainText('stopped') 

    def handleDataSent(self, data): 
     self.edit.appendPlainText('message [%d]' % 
      QtCore.QThread.currentThreadId()) 
     self.edit.appendPlainText(data['message']) 
     self.edit.appendPlainText(data['time'].toString()) 
     self.edit.appendPlainText(repr(data['items'])) 

    def handleButton(self): 
     if self._worker.isRunning(): 
      self._worker.stop() 
     else: 
      self._worker.start() 

if __name__ == '__main__': 

    app = QtWidgets.QApplication(sys.argv) 
    window = Window() 
    window.setGeometry(500, 100, 400, 400) 
    window.show() 
    sys.exit(app.exec_())