multiprocessing gui example

nonblocking_ui.py

import sys
import multiprocessing
from PyQt5 import QtWidgets


def calc():
    # random cpu bound computation
    result = 0
    for i in range(10 ** 7):
        result += i ** 2
    return result


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    w = QtWidgets.QListWidget()
    w.show()

    # populate without blocking using all your cores!
    pool = multiprocessing.Pool()
    for _ in range(32):
        pool.apply_async(calc, callback=lambda x: w.addItem(str(x)))

    app.exec_()