PyQt5 crashing with threading and progress bar - python-3.x

Question

I have a progress bar that is controlled by a start stop button. The progress bar fills up using a thread. However, whenever I run the program it crashes at random times (different time each time program is run).
class Window(QWidget):
def __init__(self):
super().__init__()
self.initUI()
self.fill_thread = None
Thread for filling progress bar. I have tried using both time.sleep and QThread.msleep.
def fill_bar(self):
while not self.stop_fill and self.completed < 100:
self.completed += 0.5
QThread.msleep(100)
self.chargeprog.setValue(self.completed)
Buttons that alternate between start and stop that call the thread
def charging(self):
if self.chargebtn.text() == 'Start':
self.chargebtn.setText('Stop')
self.chargebtn.setStyleSheet('background-color:red')
self.fill_thread = threading.Thread(target=self.fill_bar)
self.stop_fill = False
self.fill_thread.start()
else:
self.stop_fill = True
self.fill_thread.join()
self.chargebtn.setText('Start')
self.chargebtn.setStyleSheet('background-color:limegreen')

Answer 1

window.py
# -*- coding: utf-8 -*-
# Form implementation generated from reading ui file 'window.ui'
#
# Created by: PyQt5 UI code generator 5.6
#
# WARNING! All changes made in this file will be lost!
from PyQt5 import QtCore, QtGui, QtWidgets
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName("MainWindow")
MainWindow.resize(800, 600)
self.centralwidget = QtWidgets.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.progressBar = QtWidgets.QProgressBar(self.centralwidget)
self.progressBar.setGeometry(QtCore.QRect(180, 150, 118, 23))
self.progressBar.setProperty("value", 24)
self.progressBar.setObjectName("progressBar")
self.pushButton = QtWidgets.QPushButton(self.centralwidget)
self.pushButton.setGeometry(QtCore.QRect(330, 150, 75, 23))
self.pushButton.setObjectName("pushButton")
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtWidgets.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 18))
self.menubar.setObjectName("menubar")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtWidgets.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
def retranslateUi(self, MainWindow):
_translate = QtCore.QCoreApplication.translate
MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
self.pushButton.setText(_translate("MainWindow", "PushButton"))
test.py
import sys
from PyQt5.QtWidgets import QApplication,QMainWindow
from PyQt5.QtCore import QThread,pyqtSignal
from window import Ui_MainWindow
class CThread(QThread):
valueChanged = pyqtSignal([int])
def __init__(self,value):
super().__init__()
self.stop_fill = False
self.completed = value
def run(self):
while not self.stop_fill and self.completed < 100:
self.completed += 0.5
self.sleep(1)
self.valueChanged.emit(self.completed)
class Window(QMainWindow,Ui_MainWindow):
def __init__(self):
super().__init__()
super().setupUi(self)
self.fill_thread = None
self.pushButton.clicked.connect(self.charging)
def charging(self):
if self.pushButton.text() == 'Start':
self.pushButton.setText('Stop')
self.pushButton.setStyleSheet('background-color:red')
print(self.progressBar.value())
self.fill_thread = CThread(self.progressBar.value())
self.fill_thread.valueChanged.connect(self.progressBar.setValue)
self.fill_thread.start()
else:
if self.fill_thread != None:
self.fill_thread.disconnect() # event unbind
self.fill_thread.stop_fill = True
self.fill_thread.wait()
self.fill_thread.quit()
print(self.fill_thread.isRunning())
self.pushButton.setText('Start')
self.pushButton.setStyleSheet('background-color:limegreen')
if __name__ == '__main__':
app = QApplication(sys.argv)
w = Window()
w.show()
sys.exit(app.exec_())
If you want communicate between multi-threads, you can try signal/slots.