How to signal slots in a GUI from a different process?

Question

Context: In Python a main thread spawns a 2nd process (using multiprocessing module) and then launches a GUI (using PyQt4). At this point the main thread blocks until the GUI is

Answer 1

I had the same problem in C++. From a QApplication, I spawn a Service object. The object creates the Gui Widget but it's not its parent (the parent is QApplication then). To control the GuiWidget from the service widget, I just use signals and slots as usual and it works as expected. Note: The thread of GuiWidget and the one of the service are different. The service is a subclass of QObject.

If you need multi process signal/slot mechanism, then try to use Apache Thrift or use a Qt-monitoring process which spawns 2 QProcess objects.