pyqt5如何启动不在同一命令行中的多个正在进行的任务

Question

当我使用pyqt5时，界面卡住了，启动mongodb和启动jupyter在同一命令行上运行。我不知道如何修改此代码。这是我的代码，两个启动命令都被执行，并且GUI卡住了。

# -*- coding: utf-8 -*-

from PyQt5 import QtCore, QtWidgets,QtGui

from PyQt5.QtWidgets import QApplication, QMainWindow,QMessageBox,QWidget
import os
import sys
import base64


class Ui_Dialog(QWidget):
    def setupUi(self, Dialog):

        Dialog.setObjectName("Dialog")
        Dialog.resize(720, 543)
        self.msgBox = QMessageBox()

        self.mongo = QtWidgets.QPushButton(Dialog)
        self.mongo.setGeometry(QtCore.QRect(10, 40, 111, 31))
        self.mongo.setObjectName("pushButton")
        self.jupy = QtWidgets.QPushButton(Dialog)
        self.jupy.setGeometry(QtCore.QRect(160, 40, 101, 31))
        self.jupy.setObjectName("pushButton_2")
        self.lineEdit = QtWidgets.QLineEdit(Dialog)
        self.lineEdit.setGeometry(QtCore.QRect(330, 40, 131, 31))
        self.lineEdit.setObjectName("lineEdit")
        self.dj = QtWidgets.QPushButton(Dialog)
        self.dj.setGeometry(QtCore.QRect(510, 40, 131, 31))
        self.dj.setObjectName("pushButton_3")
        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)`

    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "tools"))
        self.mongo.setText(_translate("Dialog", "Startmongo"))
        self.mongo.clicked.connect(self.run_mongo)
        self.jupy.setText(_translate("Dialog", "startjupyter"))
        self.jupy.clicked.connect(self.run_junpyter)
        self.dj.setText(_translate("Dialog", "startdjango"))
        self.dj.clicked.connect(self.run_django)


    def run_mongo(self):
        os.system('mongod --dbpath d:\data\db')


    def run_junpyter(self):

        starts = 'jupyter notebook'
        os.system(starts)

    def run_django(self,starts):
        paths = self.dj_path.GetValue()
        starts ='cd /d %s && python manage.py runserver'%paths
        os.system(starts)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    MainWindow = QMainWindow()
    ui = Ui_Dialog()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

我不知道如何启动或关闭多个进程