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Python library for using asyncio in Qt-based applications

Project description


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qasync allows coroutines to be used in PyQt/PySide applications by providing an implementation of the PEP 3156 event loop.

With qasync, you can use asyncio functionalities directly inside Qt app's event loop, in the main thread. Using async functions for Python tasks can be much easier and cleaner than using threading.Thread or QThread.

If you need some CPU-intensive tasks to be executed in parallel, qasync also got that covered, providing QEventLoop.run_in_executor which is functionally identical to that of asyncio.

Basic Example

import sys
import asyncio

from qasync import QEventLoop, QApplication
from PySide6.QtWidgets import QWidget, QVBoxLayout

class MainWindow(QWidget):
    def __init__(self):

        self.lbl_status = QLabel("Idle", self)

    async def closeEvent(self, event):

    async def onMyEvent(self):

if __name__ == "__main__":
    app = QApplication(sys.argv)

    event_loop = QEventLoop(app)

    app_close_event = asyncio.Event()

    main_window = MainWindow()

    with event_loop:

More detailed examples can be found here.

The Future of qasync

qasync is a fork of asyncqt, which is a fork of quamash. qasync was created because those are no longer maintained. May it live longer than its predecessors.

qasync will continue to be maintained, and will still be accepting pull requests.


  • Python >= 3.8
  • PyQt5/PyQt6 or PySide2/PySide6

qasync is tested on Ubuntu, Windows and MacOS.

If you need Python 3.6 or 3.7 support, use the v0.25.0 tag/release.


To install qasync, use pip:

pip install qasync


You may use, modify and redistribute this software under the terms of the BSD License. See LICENSE.

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