PyQt5崩溃与QFileSystemModel和QSortFilterProxyModel ..做错什么了吗？

Question

I've had an intermittent problem with a crash when navigating a directory structure with pyqt5 on Ubuntu. Sometimes just navigating to a folder crashes, other times it is triggered by external changes to the directory being displayed. The following code is an example of the latter.

The application I'm building checks the directory being displayed when the program is activated. If it is no longer a valid directory, it moves up the tree to next valid directory. The code below simulates that by creating a directory structure, navigating down to a file and selecting it, renames the tree, then moves from the no longer valid directory up to one that is. If I run this code a few times I will see it crash, sometimes on the first execution, sometimes after a few runs.

I tried updating the mode based on seeing proxy model function in the gdb stack trace. This seemed to fix my problem, though this seems wrong to me.

I had written it off as fixed, even though I wasn't happy with the solution, but today I got crashes in this code again even with the model update.

There's not a lot of sample code out there showing how to use these classes together. Anyone see where I'm doing something wrong?

import os, sys, tempfile
from PyQt5 import QtCore, QtWidgets


class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)

        layout = QtWidgets.QVBoxLayout()
        self.setLayout(layout)
        self._view = QtWidgets.QTableView()
        layout.addWidget(self._view)

        self._model = QtWidgets.QFileSystemModel()
        self._model.setFilter(QtCore.QDir.AllDirs | QtCore.QDir.AllEntries)

        self._proxy = QtCore.QSortFilterProxyModel(self)
        self._proxy.setSourceModel(self._model)
        self._view.setModel(self._proxy)

        header = self._view.horizontalHeader()
        header.setSortIndicator(0, QtCore.Qt.AscendingOrder)
        self._proxy.sort(header.sortIndicatorSection(), header.sortIndicatorOrder())

        # Create a temporary directory structure (tmpxyz/a/b/c) starting at the location of this file
        # This is oddly very specific..less nesting or no file to select doesn't exhibit the problem!?
        path = os.path.dirname(os.path.abspath(__file__))
        self.temp_dir = tempfile.TemporaryDirectory(dir=path)
        print('created temporary directory', self.temp_dir.name)
        foo_dir = os.path.join(self.temp_dir.name, 'foo')
        os.mkdir(foo_dir)
        self.a_dir = os.path.join(foo_dir, 'a')
        os.mkdir(self.a_dir)
        b_dir = os.path.join(self.a_dir, 'b')
        os.mkdir(b_dir)
        c_dir = os.path.join(b_dir, 'c')
        os.mkdir(c_dir)
        self.temp_file_name = os.path.join(c_dir, 'foo.txt')
        with open(self.temp_file_name, 'w') as txtfile:
            print('foo', file=txtfile)

        self._model.setRootPath(c_dir)

        # moved the following to loaded..didn't seem to help
        # source_index = self._model.index(c_dir)
        # index = self._proxy.mapFromSource(source_index)
        # self._view.setRootIndex(index)

        QtCore.QTimer.singleShot(4000, self._select_temp_file)
        QtCore.QTimer.singleShot(5000, self._rename_test_dir)

        self._model.directoryLoaded.connect(self._loaded)

    def _loaded(self):
        print('_loaded')
        path = self._model.rootPath()
        print('_loaded', path)
        source_index = self._model.index(path)
        index = self._proxy.mapFromSource(source_index)
        self._view.setRootIndex(index)

    def _select_temp_file(self):
        source_index = self._model.index(self.temp_file_name)
        if source_index.isValid():
            index = self._proxy.mapFromSource(source_index)
            self._view.setCurrentIndex(index)

    # Simulate an external application moving the current directory
    def _rename_test_dir(self):
        os.rename(self.a_dir, self.a_dir+'x')
        path = self._model.rootPath()
        print('_rename_test_dir', path)
        if not os.path.isdir(path):
            def _make_valid_path(path_):
                if os.path.isdir(path_):
                    return path_
                while path_:
                    path_, _ = os.path.split(path_)
                    if os.path.isdir(path_):
                        return path_
                return '/'

            print('Path not valid:', path)
            path = _make_valid_path(path)
            print('New Path:', path)

            self._model.setRootPath(path)
            print('_rename_test_dir 5')
            # Using gdb showed a crash in the proxy model..so update it here...decreases crash frequency
            # self._proxy.setSourceModel(self._model)
            # print('_rename_test_dir 6')
            # self._view.setModel(self._proxy)
            print('_rename_test_dir 7')

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    widget = Widget()
    widget.show()
    sys.exit(app.exec_())

UPDATE:

In case it is not clear from the code, the program requires no interaction and interaction can interfere with the test. After the directory structure is created it will automatically go to the leaf level of the structure. After 4 seconds it will select the foo.txt file. Another second later it will rename the 'a' directory in the tree and then navigate back up the tree to where 'a' used to be. If all goes well the foo directory will be displayed where the 'ax' directory can be seen and the program can be exited and retried.

Executing under gbd took about 8 times before getting the following stack trace..edited down to last 2 runs:

gdb --args python3 test_qfilesystemmodel_crash2.py  
(gdb) run
Starting program: /usr/bin/python3 test_qfilesystemmodel_crash2.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe9ea5700 (LWP 21128)]
[New Thread 0x7fffdb5e5700 (LWP 21129)]
[New Thread 0x7fffdade4700 (LWP 21130)]
created temporary directory /home/myuser/Desktop/haiqu/src/tmp8dl0_uny
_loaded
_loaded /home/myuser/Desktop/haiqu/src/tmp8dl0_uny/foo/a/b/c
_rename_test_dir /home/myuser/Desktop/haiqu/src/tmp8dl0_uny/foo/a/b/c
Path not valid: /home/myuser/Desktop/haiqu/src/tmp8dl0_uny/foo/a/b/c
New Path: /home/myuser/Desktop/haiqu/src/tmp8dl0_uny/foo
_rename_test_dir 5
_rename_test_dir 7
_loaded
_loaded /home/myuser/Desktop/haiqu/src/tmp8dl0_uny/foo
[Thread 0x7fffdb5e5700 (LWP 21129) exited]
[Thread 0x7fffe9ea5700 (LWP 21128) exited]
[Thread 0x7ffff7fbb700 (LWP 21127) exited]
[Inferior 1 (process 21127) exited normally]
(gdb) run
Starting program: /usr/bin/python3 test_qfilesystemmodel_crash2.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe9ea5700 (LWP 21132)]
[New Thread 0x7fffdb5e5700 (LWP 21133)]
[New Thread 0x7fffdade4700 (LWP 21134)]
created temporary directory /home/myuser/Desktop/haiqu/src/tmpwr560n5l
_loaded
_loaded /home/myuser/Desktop/haiqu/src/tmpwr560n5l/foo/a/b/c
_rename_test_dir /home/myuser/Desktop/haiqu/src/tmpwr560n5l/foo/a/b/c
Path not valid: /home/myuser/Desktop/haiqu/src/tmpwr560n5l/foo/a/b/c
New Path: /home/myuser/Desktop/haiqu/src/tmpwr560n5l/foo
_rename_test_dir 5
_rename_test_dir 7

Thread 1 "python3" received signal SIGSEGV, Segmentation fault.
0x00007ffff5062e89 in QSortFilterProxyModel::sibling(int, int, QModelIndex const&) const ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
(gdb) bt
#0  0x00007ffff5062e89 in QSortFilterProxyModel::sibling(int, int, QModelIndex const&) const ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#1  0x00007ffff568d2d4 in ?? () from /usr/lib/python3/dist-packages/PyQt5/QtCore.cpython-35m-x86_64-linux-gnu.so
#2  0x00007ffff0af35ff in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#3  0x00007ffff00f9779 in QAccessible::updateAccessibility(QAccessibleEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#4  0x00007ffff0b028cc in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#5  0x00007ffff0b07486 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#6  0x00007ffff50cb4a9 in QMetaObject::activate(QObject*, int, int, void**) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007ffff51426e4 in QAbstractItemModel::rowsInserted(QModelIndex const&, int, int, QAbstractItemModel::QPrivateSignal) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007ffff5046f7b in QAbstractItemModel::endInsertRows() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007ffff5068246 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007ffff506a685 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007ffff506e089 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007ffff50cb4a9 in QMetaObject::activate(QObject*, int, int, void**) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#13 0x00007ffff51426e4 in QAbstractItemModel::rowsInserted(QModelIndex const&, int, int, QAbstractItemModel::QPrivateSignal) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007ffff5046f7b in QAbstractItemModel::endInsertRows() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#15 0x00007ffff0acf6e6 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#16 0x00007ffff0ad51f9 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#17 0x00007ffff50cc359 in QObject::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#18 0x00007ffff0ad58b2 in QFileSystemModel::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#19 0x00007ffff131ecdb in ?? () from /usr/lib/python3/dist-packages/PyQt5/QtWidgets.cpython-35m-x86_64-linux-gnu.so
#20 0x00007ffff08b635c in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#21 0x00007ffff08bdb11 in QApplication::notify(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#22 0x00007ffff124cdee in ?? () from /usr/lib/python3/dist-packages/PyQt5/QtWidgets.cpython-35m-x86_64-linux-gnu.so
#23 0x00007ffff509f8a0 in QCoreApplication::notifyInternal2(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#24 0x00007ffff50a202d in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#25 0x00007ffff50f3b03 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#26 0x00007ffff3b35377 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#27 0x00007ffff3b355e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#28 0x00007ffff3b3568c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#29 0x00007ffff50f3f0f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#30 0x00007ffff509d88a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#31 0x00007ffff50a5ffc in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#32 0x00007ffff1210ddb in ?? () from /usr/lib/python3/dist-packages/PyQt5/QtWidgets.cpython-35m-x86_64-linux-gnu.so
#33 0x000055555571b28f in PyCFunction_Call ()
#34 0x00005555556d21e9 in PyEval_EvalFrameEx ()
#35 0x00005555556d6d16 in ?? ()
#36 0x00005555556d7a1f in PyEval_EvalCode ()
#37 0x00005555557a4b02 in ?? ()
#38 0x00005555557a6f8d in PyRun_FileExFlags ()
#39 0x00005555557a772e in PyRun_SimpleFileExFlags ()
#40 0x00005555557d72e7 in Py_Main ()
#41 0x0000555555667b31 in main ()
(gdb) 

Answer 1

I'm writing this off as an old library problem. After updating to pyqt5.8 and python3.6 I am no longer able to reproduce the crash. Thanks for the help.