shiboken segfault, (py) object already deleted

[mlampert]

I get a significant number of segfaults which seem to have to do with objects being ref-counted wrong. Most of them are during shutdown of FC, rarely during operation. The stacktrace looks something like this:

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Program received signal SIGSEGV, Segmentation fault.
#0  /lib/x86_64-linux-gnu/libc.so.6(+0x3a100) [0x7f72d5624100]
#1  0x7f72d48c1822 in Shiboken::BindingManager::retrieveWrapper(void const*) from /usr/lib/x86_64-linux-gnu/libshiboken2.cpython-37m-x86_64-linux-gnu.so.5.11+0x12
#2  /usr/lib/x86_64-linux-gnu/libpyside2.cpython-37m-x86_64-linux-gnu.so.5.11(+0x2c795) [0x7f72d4898795]
#3  /usr/lib/x86_64-linux-gnu/libpyside2.cpython-37m-x86_64-linux-gnu.so.5.11(+0x2e167) [0x7f72d489a167]
#4  0x7f72d5c2fb5a in QMetaType::destruct(int, void*) from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5+0xca
#5  /usr/lib/x86_64-linux-gnu/libQt5Core.so.5(+0x2b863c) [0x7f72d5c5563c]
#6  0x7f72d5c55c97 in QVariant::~QVariant() from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5+0x47
#7  0x7f72d5c43b04 in QObjectPrivate::~QObjectPrivate() from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5+0x314
#8  0x7f72d5c43bf9 in QObjectPrivate::~QObjectPrivate() from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5+0x9
#9  0x7f72d5c4c477 in QObject::~QObject() from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5+0x607
#10  /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5(+0x1aa059) [0x7f72d6082059]
#11  /lib/x86_64-linux-gnu/libc.so.6(+0x3c720) [0x7f72d5626720]
#12  /lib/x86_64-linux-gnu/libc.so.6(+0x3c85a) [0x7f72d562685a]
#13  /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf2) [0x7f72d5610bc2]
#14  /home/markus/projects/FreeCAD/dev/build/bin/FreeCAD(_start+0x2a) [0x557004f214ca]

I get a similar issue, although handled gracefully when closing a Path op task panel. This happens quite frequently - I'm not aware of any changes in Path related to this behaviour:

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Traceback (most recent call last):                                                             
  File "/media/sdb/projects/FreeCAD/dev/build/Mod/Path/PathScripts/PathOpGui.py", line 946, in reject                                                                                         
    PathUtil.clearExpressionEngine(self.obj)                                                   
  File "/media/sdb/projects/FreeCAD/dev/build/Mod/Path/PathScripts/PathUtil.py", line 135, in clearExpressionEngine                                                                           
    if hasattr(obj, 'ExpressionEngine'):                                                       
<class 'ReferenceError'>: Cannot access attribute 'ExpressionEngine' of deleted object   

Anybody else seeing this or similar issues?

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OS: Debian GNU/Linux bullseye/sid (LXQt//usr/share/xsessions/lxqt)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.19018 +2 (Git)
Build type: Unknown
Branch: feature/toggle-active-cmd-support-for-dressups
Hash: f6d233942ebc6b80109aad23d28af1d3e95a810a
Python version: 3.7.5
Qt version: 5.12.5
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: C/Default (C)

[kkremitzki]

The most recent pyside2 upload to Debian Unstable has some shiboken2 related bugs, this might be a manifestation of that. If it's the case you could grab the previous version off e.g. tracker.debian.org and see if recompiling with that version fixes things.

[mlampert]

Not sure when those errors got introduced but this is not a new phenomenon. I'm running testing (not unstable) and these crashes and errors have been happening for a few weeks now.