使用concurrent.futures.ThreadPoolExecutor()时PyQt5小部件

Question

我一直在尝试使用concurrent.futures.ThreadPoolExecutor()在我的应用程序中运行一些后台任务，以便在这些任务（“测量”）运行时我能够与 GUI 进行交互。这些任务完成后，我分配一个回调函数来更新 GUI 的某些字段，然后尝试根据这些字段更新 GUI 小部件（绘图、表格、列表等）。这是一个例子：class MainWindow(QtWidgets.QMainWindow):        def __init__(self):        super(MainWindow, self).__init__()        *some more code goes here*        self.executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)    def perform_measurement():        future = self.executor.submit(*a function*)        future.add_done_callback(self.update_gui_fields)    def update_gui_fields(self, future):        data = future.result()        self.items_for_list.append(QStandardItem(data['key']))        *more fields are updated here*        self.QListView1.setModel(self.items_for_list)        *more widgets are updated here*问题是字段已正常更新，但是当我尝试与小部件交互时，应用程序崩溃了。这是因为子级（此处为）与父级（此处为）self.items_for_list位于不同的线程中。self.QListView1这是我得到的错误：QObject: Cannot create children for a parent that is in a different thread.(Parent is QListView(0x555795efbc10), parent's thread is QThread(0x555795296600), current thread is QThread(0x7fd12400a100)QBasicTimer::start: QBasicTimer can only be used with threads started with QThread我在之前的帖子中找不到任何解决方案。知道如何攻击这个吗？谢谢！

Answer 1

与 add_done_callback 关联的回调在辅助线程中执行，根据您的代码，您正尝试从该辅助线程更新 GUI，这是禁止的，因此 Qt 会抛出该警告。解决方案是通过创建一个通过信号转发该信息的 QObject 来实现逻辑：

import concurrent.futures

import sys

import time

from PyQt5 import QtCore, QtGui, QtWidgets

def measure():

    time.sleep(5)

    return {"key": "value"}

class TaskManager(QtCore.QObject):

    finished = QtCore.pyqtSignal(object)

    def __init__(self, parent=None, max_workers=None):

        super().__init__(parent)

        self._executor = concurrent.futures.ThreadPoolExecutor(max_workers=max_workers)

    @property

    def executor(self):

        return self._executor

    def submit(self, fn, *args, **kwargs):

        future = self.executor.submit(fn, *args, **kwargs)

        future.add_done_callback(self._internal_done_callback)

    def _internal_done_callback(self, future):

        data = future.result()

        self.finished.emit(data)

class MainWindow(QtWidgets.QMainWindow):

    def __init__(self):

        super(MainWindow, self).__init__()

        self.model = QtGui.QStandardItemModel()

        self.view = QtWidgets.QListView()

        self.view.setModel(self.model)

        self.button = QtWidgets.QPushButton("launch")

        self._manager = TaskManager(max_workers=1)

        self._manager.finished.connect(self.update_gui_fields)

        self.button.clicked.connect(self.perform_measurement)

        central_widget = QtWidgets.QWidget()

        self.setCentralWidget(central_widget)

        lay = QtWidgets.QVBoxLayout(central_widget)

        lay.addWidget(self.view)

        lay.addWidget(self.button)

    def perform_measurement(self):

        self._manager.submit(measure)

    def update_gui_fields(self, data):

        self.model.appendRow(QtGui.QStandardItem(data["key"]))

if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()

    w.show()

    sys.exit(app.exec_())