Greeting

I am trying to make QProgressBar with QThread.
but it’s not working.
I used threads, but it seems as if everything runs on the main thread.

it’s my code

import sys
from PySide6.QtWidgets import QApplication, QProgressBar, QWidget, QPushButton, QVBoxLayout
from PySide6.QtCore import QThread, Signal
import time


class Thread(QThread):
    change_value = Signal()

    def run(self):
        self.change_value.emit()
            
class Form(QWidget):
    def __init__(self):
        QWidget.__init__(self)
        self.pgsb = QProgressBar()
        self.pb = QPushButton("Pause")
        self.th = Thread()
        self.init_widget()
        self.th.change_value.connect(self.update_progressbar)
        self.th.start()

    def init_widget(self):
        layout = QVBoxLayout()
        self.setLayout(layout)
        layout.addWidget(self.pgsb)
        layout.addWidget(self.pb)

    def update_progressbar(self):
        cnt = 0
        while True:
            if cnt == 100:
                cnt = 0
            cnt += 1
            self.pgsb.setValue(cnt)
            time.sleep(0.5)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    form = Form()
    form.show()
    sys.exit(app.exec())

it is not working.
However, the following code works fine.

import sys
from PySide6.QtWidgets import QApplication, QProgressBar, QWidget, QPushButton, QVBoxLayout
from PySide6.QtCore import QThread, Signal
import time


class Thread(QThread):
    change_value = Signal(int)

    def run(self):
        cnt = 0
        while True:
            if cnt == 100:
                cnt = 0
            cnt += 1
            self.change_value.emit(cnt)
            time.sleep(0.5)


class Form(QWidget):
    def __init__(self):
        QWidget.__init__(self)
        self.pgsb = QProgressBar()
        self.th = Thread()
        self.init_widget()
        self.th.change_value.connect(self.update_progressbar)
        self.th.start()

    def init_widget(self):
        layout = QVBoxLayout()
        self.setLayout(layout)
        layout.addWidget(self.pgsb)

    def update_progressbar(self, value):
        self.pgsb.setValue(value)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    form = Form()
    form.show()
    sys.exit(app.exec())

Based on what is currently happening, the first code appears to cause UI updates on the main thread.
But I don’t understand. Why is the result of this code different?