-
Bug
-
Resolution: Invalid
-
Not Evaluated
-
None
-
6.8
-
None
-
macOS,
Windows
It's first reported here.
The slot is always executed in the signal caller's thread, even with explicit QueuedConnection, when a worker approach is used. The following minimal example is almost identical to the example from the official document.
import sys from PySide6.QtCore import QObject, Signal, QThread, Qt, Slot from PySide6.QtWidgets import QMainWindow, QApplication class Worker(QObject): update = Signal() def run(self): print(f"worker: {QThread.currentThread().objectName()}") self.update.emit() class Window(QMainWindow): def __init__(self, parent=None): super().__init__(parent) worker = Worker() thread = QThread(self) thread.setObjectName('test thread') worker.moveToThread(thread) thread.started.connect(worker.run) worker.update.connect(self.update) thread.start() @Slot() def update(self): print(f"window: {QThread.currentThread().objectName()}") if __name__ == '__main__': app = QApplication() w = Window() w.show() sys.exit(app.exec())
The output is
worker: Qt mainThread window: test thread
However, the problem doesn't exist when switched to subclassing QThread:
import sys from PySide6.QtCore import QObject, Signal, QThread, Qt, Slot from PySide6.QtWidgets import QMainWindow, QApplication class Thread(QThread): update = Signal() def run(self): print(f"thread: {QThread.currentThread().objectName()}") self.update.emit() class Window(QMainWindow): def __init__(self, parent=None): super().__init__(parent) thread = Thread(self) thread.setObjectName('test thread') thread.update.connect(self.update) thread.start() @Slot() def update(self): print(f"window: {QThread.currentThread().objectName()}") if __name__ == '__main__': app = QApplication() w = Window() w.show() sys.exit(app.exec())
I tried the cpp equivalent version and it works fine. Source code is attached in the zip file. Result of cpp version:
2025-01-21 18:19:49.155575-0500 qt_test[86901:106814649] Worker::process "test thread" 2025-01-21 18:19:50.033013-0500 qt_test[86901:106814599] Window::process "Qt mainThread"
- links to