[PyQt] Segfault on PyQt 5.9.1 on Windows

[Valentin Valls]

Hi,

I am trying to debug a software on Windows using the last PyQt.

I compile all the expected libraries in debug mode

- cpython 3.6
- PyQt 5.9.1
- Qt 5.9.2
- sip 4.19.5

As result this following code often create segfault in release mode
(using the last release from pypi), and an infinite loop in debug mode.

from PyQt5 import Qt
qapp = Qt.QApplication([])
Qt.QThreadPool.globalInstance()
# the problem occurs when you exist the python interpreter

The infinite loop is on the SIP side: objmap.c line 102:

    while ((hek = om -> hash_array[hash].key) != NULL && hek != key)
        hash = (hash + inc) % om -> size;

Here is the backtrace:

    sip_d.pyd!findHashEntry(sipObjectMap * om, void * key) Line 103    C
    sip_d.pyd!sipOMFindObject(sipObjectMap * om, void * key, const
_sipTypeDef * td) Line 116    C
    sip_d.pyd!sip_api_get_pyobject(void * cppPtr, const _sipTypeDef *
td) Line 8934    C
    QtCore_d.pyd!PyQtMonitor::on_destroyed(QObject * cppInst) Line
106    C++
    QtCore_d.pyd!PyQtMonitor::qt_static_metacall(QObject * _o,
QMetaObject::Call _c, int _id, void * * _a) Line 75    C++
    Qt5Cored.dll!QMetaObject::activate(QObject * sender, int
signalOffset, int local_signal_index, void * * argv) Line 3768    C++
    Qt5Cored.dll!QMetaObject::activate(QObject * sender, const
QMetaObject * m, int local_signal_index, void * * argv) Line 3629    C++
    Qt5Cored.dll!QObject::destroyed(QObject * _t1) Line 216    C++
    Qt5Cored.dll!QObject::~QObject() Line 901    C++
    Qt5Cored.dll!QThreadPool::~QThreadPool() Line 448    C++
    [External Code]   
    python36_d.dll!Py_Exit(int sts) Line 1551    C
    python36_d.dll!handle_system_exit() Line 604    C
    python36_d.dll!PyErr_PrintEx(int set_sys_last_vars) Line 614    C
    python36_d.dll!PyErr_Print() Line 509    C
    python36_d.dll!PyRun_InteractiveOneObject(_iobuf * fp, _object *
filename, PyCompilerFlags * flags) Line 237    C
    python36_d.dll!PyRun_InteractiveLoopFlags(_iobuf * fp, const char *
filename_str, PyCompilerFlags * flags) Line 112    C
    python36_d.dll!PyRun_AnyFileExFlags(_iobuf * fp, const char *
filename, int closeit, PyCompilerFlags * flags) Line 74    C
    python36_d.dll!run_file(_iobuf * fp, const wchar_t * filename,
PyCompilerFlags * p_cf) Line 338    C
    python36_d.dll!Py_Main(int argc, wchar_t * * argv) Line 809    C
    python_d.exe!wmain(int argc, wchar_t * * argv) Line 15    C
    [External Code]   

The global thread pool is then not usable.

I also have segfault and deadlock when using an own QThreadPool; i suspect
Qt.QIcon(filename) to have a strange behaviour when it is released at the
end of the program; and segfault when reusing 2 time index created by createIndex
from custom QAbstractItemModel.
Here (https://github.com/silx-kit/silx/pull/1344
) is the different tweaks i used to be able to have no segfault
in our continuous integration tests.
But right now i don't have simple reproducible examples.

Anyway, is the use of the globalInstance is reproducible on your side?
Do you have any idea?
Hope this feedback can help. Thanks a lot.

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