从Windows cmd或IDLE运行时出现“QThread：在线程仍在运行时被销毁”的错误，但从PyCharm中运行则没有？

Question

这是一个使用QObject.moveToThread实现PyQt多线程的简化程序版本。基本上，我在单独的线程中查询网页并提取HTML内容。

当我从IDLE或Windows命令行运行代码时，会出现问题，Python会挂起。Windows cmd显示“QThread：在线程仍在运行时被销毁”。但是，如果我从Pycharm运行它，一切都正常。

您可以在这里获取.ui文件。

有什么想法吗？

import requests
import sys
from PyQt4 import QtGui, uic
from PyQt4.QtCore import QObject, pyqtSlot, pyqtSignal, QThread


qtCreatorFile = "window.ui"
Ui_MainWindow, QtBaseClass = uic.loadUiType(qtCreatorFile)


class HttpClient(QObject):

    finished =  pyqtSignal(str)

    def __init__(self):
        QObject.__init__(self)

    @pyqtSlot()
    def retrieve_page(self, url):
        response = requests.get(url)
        self.finished.emit(response.text)


class HtmlGetter(QtGui.QMainWindow, Ui_MainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        Ui_MainWindow.__init__(self)
        self.setupUi(self)       
        self.go_button.clicked.connect(self.query_page)

    def query_page(self):
        http_client = HttpClient()
        temp_thread = QThread()
        http_client.moveToThread(temp_thread)

        temp_thread.started.connect(
        lambda: http_client.retrieve_page("http://www.google.com/"))
        http_client.finished.connect(self.show_html)

        # Terminating thread gracefully.
        http_client.finished.connect(temp_thread.quit)
        http_client.finished.connect(http_client.deleteLater)
        temp_thread.finished.connect(temp_thread.deleteLater)

        temp_thread.start()

    def show_html(self, html_text):
        print(html_text)


def main():
    app = QtGui.QApplication(sys.argv)
    window = HtmlGetter()
    window.show()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

- R01k

---

每当我在Windows上运行多线程的pyqt程序时，尤其是当我尝试使用Ctrl-C来终止它时，我也会遇到这个问题。 - ClydeTheGhost

Answer 1

我明白了：

http_client和temp_thread都必须成为HtmlGetter类的属性。我认为这是因为，否则Python在退出函数时会丢弃它们。这是可行的代码：

import requests
import sys
from PyQt4 import QtGui, uic
from PyQt4.QtCore import QObject, pyqtSlot, pyqtSignal, QThread


qtCreatorFile = "window.ui"
Ui_MainWindow, QtBaseClass = uic.loadUiType(qtCreatorFile)


class HttpClient(QObject):

    finished =  pyqtSignal()
    send_text = pyqtSignal(str)

    def __init__(self):
        QObject.__init__(self)

    @pyqtSlot()
    def retrieve_page(self, url):
        response = requests.get(url)
        self.send_text.emit(response.text)
        self.finished.emit()


class HtmlGetter(QtGui.QMainWindow, Ui_MainWindow):

    def __init__(self):
        QtGui.QMainWindow.__init__(self)
        Ui_MainWindow.__init__(self)
        self.setupUi(self)       
        self.go_button.clicked.connect(self.query_page)

    def query_page(self):
        self.http_client = HttpClient()
        self.temp_thread = QThread()
        self.http_client.moveToThread(self.temp_thread)

        self.temp_thread.started.connect(
        lambda: self.http_client.retrieve_page("http://www.google.com/"))
        self.http_client.send_text.connect(self.show_html)

        # Terminating thread gracefully.
        self.http_client.finished.connect(self.temp_thread.quit)
        self.http_client.finished.connect(self.http_client.deleteLater)
        self.temp_thread.finished.connect(self.temp_thread.deleteLater)

        self.temp_thread.start()

    def show_html(self, html_text):
        print(html_text)


def main():
    app = QtGui.QApplication(sys.argv)
    window = HtmlGetter()
    window.show()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

- R01k