async_gui

async_gui is a library aimed to make use of threads in GUI applications simpler. It’s inspired by PyCon talk Using futures for async GUI programming in Python 3.3 and tornado @gen.engine implementation.

Most of GUI toolkits don’t allow you to access graphical elements from non-GUI thread. Python 3.2+ has nice new feature concurrent.futures, but we can’t just wait for result from future and callbacks are not very handy.

Combination of Coroutines via Enhanced Generators (PEP-342) and futures creates a rich and easy to use asynchronous programming model which can be used for creating highly responsive GUI applications.

Example

Demo of button click handler:

@engine.async
def on_button_click(self, *args):
    self.status_label.setText("Downloading image...")
    # Run single task in separate thread
    image_data = yield Task(self.load_url,
                            "http://www.google.com/images/srpr/logo4w.png")
    pixmap = QtGui.QPixmap.fromImage(QtGui.QImage.fromData(image_data))
    self.image_label.setPixmap(pixmap)
    self.status_label.setText("Downloading pages...")
    urls = ['http://www.google.com',
            'http://www.yandex.ru',
            'http://www.python.org']
    # Run multiple task simultaneously in thread pool
    pages = yield [Task(self.load_url, url) for url in urls]
    self.status_label.setText("Done")
    avg_size = sum(map(len, pages)) / len(pages)
    self.result_label.setText("Average page size: %s" % avg_size)

Tasks yielded from on_button_click() executed in thread pool, but GUI updates done in the GUI thread. For CPU-bound applications there is also ability to run tasks in pool of processes.

See full example in examples directory.

Features

• Python 2.7+ (futures required), Python 3+ support

• PyQt4/PySide, Tk, Wx, Gtk GUI toolkits support. Easy to add another

• Can execute tasks in Thread, Process, Greenlet (gevent required)

• Possibility to run multiple tasks at the same time

• Straightforward exception handling

• Full test coverage

Installation

Using pip:

$ pip install async_gui

Or download, unpack and:

$ python setup.py install

To run tests use:

$ python setup.py test

Links

• Documentation at readthedocs.org

• Source code and issue tracking at GitHub.

History