qt_multiprocessing
Long running process that runs along side of the Qt event loop and allows other widgets to live in the other process.
Quick Start
import os
import qt_multiprocessing
from qtpy import QtWidgets
class MyPIDLabel(QtWidgets.QLabel):
def print_pid(self):
text = self.text()
print(text, 'PID:', os.getpid())
return text
class MyPIDLabelProxy(qt_multiprocessing.WidgetProxy):
PROXY_CLASS = MyPIDLabel
GETTERS = ['text']
if __name__ == '__main__':
with qt_multiprocessing.MpApplication() as app:
print("Main PID:", os.getpid())
# Proxy
lbl = MyPIDLabelProxy("Hello")
widg = QtWidgets.QDialog()
lay = QtWidgets.QFormLayout()
widg.setLayout(lay)
# Form
inp = QtWidgets.QLineEdit()
btn = QtWidgets.QPushButton('Set Text')
lay.addRow(inp, btn)
def set_text():
text = inp.text()
lbl.setText(inp.text())
# Try to somewhat prove that the label is in a different process.
# `print_pid` Not exposed (will call in other process. Result will be None)
print('Set Label text', text + '. Label text in this process', lbl.print_pid())
# `print_pid` will run in a separate process and print the pid.
btn.clicked.connect(set_text)
widg.show()Below is an example for if you want to manually create widgets in a different process without the proxy.
import os
import qt_multiprocessing
from qtpy import QtWidgets
class MyPIDLabel(QtWidgets.QLabel):
def print_pid(self):
text = self.text()
print(text, 'PID:', os.getpid())
return text
def create_process_widgets():
lbl = MyPIDLabel('Hello')
lbl.show()
return {'label': lbl}
if __name__ == '__main__':
with qt_multiprocessing.MpApplication(initialize_process=create_process_widgets) as app:
print("Main PID:", os.getpid())
widg = QtWidgets.QDialog()
lay = QtWidgets.QFormLayout()
widg.setLayout(lay)
# Form
inp = QtWidgets.QLineEdit()
btn = QtWidgets.QPushButton('Set Text')
lay.addRow(inp, btn)
def set_text():
text = inp.text()
app.add_var_event('label', 'setText', text)
# The label does not exist in this process at all. Can only access by string names
print('Set Label text', text + '.')
# `print_pid` will run in a separate process and print the pid.
app.add_var_event('label', 'print_pid')
btn.clicked.connect(set_text)
widg.show()How it works
This library works by creating an event loop in a separate process while the Qt application is running in the main process. This library is built off of the mp_event_loop library which creates a long running process where events are thrown on a queue and executed in a separate process. The other process that is created also runs it's own Qt application while executing events in a timer.
This library has the ability to:
- dynamic creation of widgets in a separate process
- Run methods of widgets in a separate process through variable names
- Proxy widgets
Manual Example
This example shows how everything comes together manually
import os
import qt_multiprocessing
from qtpy import QtWidgets
class MyPIDLabel(QtWidgets.QLabel):
def print_pid(self):
text = self.text()
print(text, 'PID:', os.getpid())
return text
def create_process_widgets():
lbl = MyPIDLabel('Hello')
lbl.show()
return {'label': lbl}
if __name__ == '__main__':
app = QtWidgets.QApplication([])
mp_loop = qt_multiprocessing.AppEventLoop(initialize_process=create_process_widgets)
print("Main PID:", os.getpid())
widg = QtWidgets.QDialog()
lay = QtWidgets.QFormLayout()
widg.setLayout(lay)
# Form
inp = QtWidgets.QLineEdit()
btn = QtWidgets.QPushButton('Set Text')
lay.addRow(inp, btn)
def set_text():
text = inp.text()
mp_loop.add_var_event('label', 'setText', text)
# The label does not exist in this process at all. Can only access by string names
print('Set Label text', text + '.')
# `print_pid` will run in a separate process and print the pid.
mp_loop.add_var_event('label', 'print_pid')
btn.clicked.connect(set_text)
widg.show()
# Run the multiprocessing event loop
mp_loop.start()
# Run the application event loop
app.exec_()
# Quit the multiprocessing event loop when the app closes
mp_loop.close()
