python qt5应用程序中线程的正确模式是什么? [英] What's the correct pattern for threading in a python qt5 application?

问题描述

我正在尝试编写一个长时间运行但不是 CPU 密集型进程的 pyqt5 应用程序.我希望能够在不挂起 UI 的情况下运行它，所以我正在尝试使用线程，但是因为我似乎不能只运行一个线程并在它完成代码后让它停止，以便它可以再次运行，我已经尝试将线程设置为在运行之前等待变量更改.

I'm trying to write a pyqt5 application with a long running, but not CPU intensive process. I'd like to be able to run it without hanging the UI, so I'm trying to use threading, but since it doesn't seem like I can just run a thread and have it stop after its gone through its code so that it can be run again, I've tried setting up the thread to wait for a variable to change before running.

我知道这不是在 pyqt 应用程序中运行长进程的正确模式.

I know this can't be the correct pattern for running long processes in a pyqt app.

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()

推荐答案

下面是一个简单的演示，展示了如何启动和停止工作线程，以及如何安全地与 gui 线程通信.

Below is a simple demo showing how to start and stop a worker thread, and safely comminucate with the gui thread.

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_())

这篇关于python qt5应用程序中线程的正确模式是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！