PySide2 - multi-threading cases Python crashs

[wzzgdcn]

The program is trying to do some work at a newly created qthread and send the data to GUI thread to show.
Refer this link manipulating-widget-in-pyside2-qthread-causes-python3-not-responding for some background.
Does anyone know this is the coding issue or an pyside2 bug?

Crash after a long run (100% reproduce, a few minutes or more, it depends) at env:
Python3.6.8 32bit， WIN10 X64, Pyside2 5.12.1

Fatal Python error: GC object already tracked

Current thread 0x000019a8 (most recent call first):
  File "C:\Python36-32\lib\ntpath.py", line 89 in join
  File "D:/project/demo.py", line 25 in list_folder
  File "D:/project/demo.py", line 29 in list_folder
  File "D:/project/demo.py", line 35 in run

Thread 0x000034b8 (most recent call first):
  File "D:/project/demo.py", line 74 in addTopItem
  File "D:/project/demo.py", line 105 in <module>

Process finished with exit code -1073740791 (0xC0000409)

Work with no problem (tested at least half an hour, try several times) at env:
Python3.6.8 32bit， WIN10 X64, PyQt5 5.12

Modify USE_PYSIDE2 = True/False to switch between pyside2 and pyqt5.

# -*- coding: utf-8 -*-
import os

USE_PYSIDE2 = True
if USE_PYSIDE2:
    from PySide2 import QtWidgets, QtGui, QtCore
    from PySide2.QtCore import Signal
else:
    from PyQt5 import QtWidgets, QtGui, QtCore
    from PyQt5.QtCore import pyqtSignal as Signal


class ShowFolderTreeThread(QtCore.QThread):
    addTopItem = Signal(str, str, tuple)

    def __init__(self, p, root_dir: str = "."):
        super().__init__(p)
        self.root_dir = root_dir

    def list_folder(self, parent_path: str, max_depth: int = 3, parent_item_ids=tuple()):
        if max_depth <= 0:
            return
        try:
            for row, content in enumerate(os.listdir(parent_path)):
                content_path = os.path.join(parent_path, content)
                is_dir: bool = os.path.isdir(content_path)
                self.addTopItem.emit(content, "Folder" if is_dir else os.path.splitext(content)[1], parent_item_ids)
                if is_dir:
                    self.list_folder(content_path, max_depth - 1, (*parent_item_ids, row))
        except Exception as e:
            print("list_folder", type(e), e)

    def run(self):
        try:
            self.list_folder(self.root_dir)
        except Exception as e:
            print(type(e), e)


class MainWindow(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.treeWidget = QtWidgets.QTreeWidget(self)
        self.treeWidget.setColumnCount(2)
        self.treeWidget.setHeaderLabels(["name", "type", ])
        self.treeWidget.setColumnWidth(0, 250)

        self.pushButton = QtWidgets.QPushButton(self)
        self.pushButton.setText("&Refresh")

        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.treeWidget)
        layout.addWidget(self.pushButton)
        self.setLayout(layout)

        self.resize(400, 600)

        home = os.path.expanduser('~')
        self.workThread = ShowFolderTreeThread(self, home)

        self.workThread.finished.connect(self.thread_finished)
        self.workThread.addTopItem.connect(self.addTopItem)
        self.pushButton.clicked.connect(self.start_thread)

        self.timer = QtCore.QTimer()
        self.timer.setInterval(10)
        self.timer.setSingleShot(True)
        self.timer.timeout.connect(self.pushButton.click)
        self.timer.start()

    def addTopItem(self, content: str, content_type: str, parent_item_ids: tuple):
        item = QtWidgets.QTreeWidgetItem()
        item.setText(0, content)
        item.setText(1, content_type)
        if parent_item_ids:
            index, *item_ids = parent_item_ids
            parent_item = self.treeWidget.topLevelItem(index)
            for i in item_ids:
                parent_item = parent_item.child(i)
            parent_item.addChild(item)
        else:
            self.treeWidget.addTopLevelItem(item)

    def start_thread(self):
        self.pushButton.setDisabled(True)
        self.treeWidget.clear()
        self.workThread.start()

    def thread_finished(self):
        self.pushButton.setEnabled(True)
        self.timer.start()

    def closeEvent(self, event: QtGui.QCloseEvent):
        self.timer.stop()
        super().closeEvent(event)


if __name__ == '__main__':
    import sys

    try:
        app = QtWidgets.QApplication(sys.argv)
        w = MainWindow()
        w.show()
        sys.exit(app.exec_())
    except Exception as e:
        print(type(e), e)
        raise e

[Alfalfa]

Just a guess, instead of subclassing QThread, perhaps it would work better with the moveToThread method.

https://gitlab.com/snippets/1732597

[Godwin]

You should use the default threading available as a standard python library for your threads. Its called "threading", just "threading". It's very, very simple.