PyQT: How to show elapsed time after pressing a button

Question

In this simple example I want to have:

• a button which starts doing 2 seconds of work
• a label which shows for how long the work has been running

When I run my file, it works fine but shows:

QObject::killTimer: Timers cannot be stopped from another thread

I'm new to PyQT, I have no idea how to fix this.

Does it even make sense to use threading.Thread, or should I use QThread for my use-case, or some entirely different code organization?

Is it common to use threading to not block the GUI or am I reinventing the wheel?

from PySide6.QtWidgets import (
    QApplication, QWidget, QVBoxLayout, QPushButton, QLabel
)
from PySide6.QtCore import QTime, QTimer
import threading
import time


class MyWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.resize(200, 100)
        self.button = QPushButton('Do work', self)
        self.button.clicked.connect(self.run_work_thread)
        self.timer_label = QLabel('', self)  # hide label at the start (but save its space)
        layout = QVBoxLayout(self)
        layout.addWidget(self.button)
        layout.addWidget(self.timer_label)
        self.setLayout(layout)

    def run_work_thread(self):
        """Do work in a separate thread, not to block the GUI"""
        self.button.setEnabled(False)
        thread = threading.Thread(target=self.do_work)
        thread.start()

        self.start_time = QTime(0, 0, 0)
        self.timer = QTimer(self)
        self.timer_label.setText('Doing work for: 0 s')
        self.timer.timeout.connect(self.update_timer)
        self.timer.start(1000)  # update every 1 sec

    def do_work(self):
        time.sleep(2)  # Simulate work
        self.timer.stop()
        self.timer_label.setText('')  # clear the timer label
        self.button.setEnabled(True)

    def update_timer(self):
        """Update the timer, and its label with the elapsed time"""
        self.start_time = self.start_time.addMSecs(1000)
        self.timer_label.setText(f'Doing work for: {self.start_time.toString("s")} s')


if __name__ == '__main__':
    app = QApplication([])
    window = MyWindow()
    window.show()
    app.exec()

Answer 1

Following the @musicamante 's helpful suggestion, here is the solution I did:

from PySide6.QtWidgets import (
    QApplication, QWidget, QVBoxLayout, QPushButton, QLabel
)
from PySide6.QtCore import QTime, QTimer, QThread, Signal
import time


class Worker(QThread):
    def run(self):
        time.sleep(2)  # Simulate work


class MyWindow(QWidget):
    def __init__(self):
        super().__init__()
        self.resize(200, 100)
        self.button = QPushButton('Do work', self)
        self.button.clicked.connect(self.run_work)
        self.timer_label = QLabel('', self)
        layout = QVBoxLayout(self)
        layout.addWidget(self.button)
        layout.addWidget(self.timer_label)
        self.setLayout(layout)

        ### ADDED: ###
        self.worker = Worker()
        self.worker.finished.connect(self.on_work_finished)
        ##############

    def run_work(self):
        """Start the work and the timer"""
        self.button.setEnabled(False)
        self.start_time = QTime(0, 0, 0)
        self.timer = QTimer(self)
        self.timer_label.setText('Doing work for: 0 s')
        self.timer.timeout.connect(self.update_timer)
        self.timer.start(1000)  # update every 1 sec
        self.worker.start()

    def on_work_finished(self):
        """Stop the timer and reset the UI when work is done"""
        self.timer.stop()
        self.timer_label.setText('')
        self.button.setEnabled(True)

    def update_timer(self):
        """Update the timer and its label with the elapsed time"""
        self.start_time = self.start_time.addSecs(1)
        self.timer_label.setText(f'Doing work for: {self.start_time.toString("s")} s')

if __name__ == '__main__':
    app = QApplication([])
    window = MyWindow()
    window.show()
    app.exec()