Re: Crash-on-exit after call to app.processEvents()
"V. Armando Sole" <[email protected]> Mon, 25 May 2020 22:38:05 +0200
| Newsgroups | gmane.comp.python.pyqt-pykde |
|---|---|
| Message-ID | <[email protected]> |
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Hi Ray,
I do not know if it will help your case. I was getting rid of some
crashes on exit by deleting all widgets that had no parent. For
instance, when closing the QMainWindow by doing:
def closeEvent(self, event):
if __name__ == "__main__":
app = qt.QApplication.instance()
allWidgets = app.allWidgets()
for widget in allWidgets:
try:
# we cannot afford to crash here
if id(widget) != id(self):
if widget.parent() is None:
widget.close()
except:
_logger.debug("Error closing widget")
return qt.QMainWindow.closeEvent(self, event)
Best regards,
Armando
On 25.05.2020 19:48, Raymond Osborn wrote:
> I added a call to QtWidgets.QApplication.instance().processEvents() in order to force adjustResize() to work when switching tabs (that's another story). It succeeded in fixing my resize issue, but now it triggers a segfault when I exit the application. This seemed to be related to the bug described in https://www.riverbankcomputing.com/static/Docs/PyQt5/gotchas.html#crashes-on-exit. One fix, suggested by @ekhumoro on stackoverflow (https://stackoverflow.com/questions/59120337/why-does-pyqt-sometimes-crash-on-exit) was to delete the main window and the app first, but that doesn't seem to fix it. I am running PyQt 5.12 because that is the last version supported by conda, so I can't test the one-exit fix in v5.13, and my users probably wouldn't have it installed anyway. It happens on Macs a
nd linux.
>
> What I am asking is if there are additional things to try in addition to @ekhumoro's suggestion? Basically he suggests doing something like:
>
> def main():
> app = QApplication(sys.argv)
> main_window = MainWindow()
> main_window.show()
> app.exec_()
> # ensure correct deletion order
> del main_window, app
>
> Does anyone understand why the crash only occurs if I have calls to processEvents() in the code? It never happens when I remove them.
>
> Thanks,
> Ray
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<p>Hi Ray,</p>
<p>I do not know if it will help your case. I was getting rid of some crash=
es on exit by deleting all widgets that had no parent. For instance, when c=
losing the QMainWindow by doing:</p>
<p> def closeEvent(self, event):<br /> &=
nbsp; if __name__ =3D=3D "__main__":<br /> &nb=
sp; app =3D qt.QApplication=
=2Einstance()<br /> &n=
bsp; allWidgets =3D app.allWidgets()<br /> &nb=
sp; for widget in allWidgets:<br />&nbs=
p; &=
nbsp; try:<br />  =
; # we cannot a=
fford to crash here<br /> &n=
bsp; if id(widg=
et) !=3D id(self):<br /> &nb=
sp; =
if widget.parent() is None:<br />  =
; &n=
bsp; widget.close()<b=
r />  =
; except:<br /> =
_l=
ogger.debug("Error closing widget")<br /> &nbs=
p; return qt.QMainWindow.closeEvent(self, event)</p>
<p>Best regards,</p>
<p>Armando</p>
<p>On 25.05.2020 19:48, Raymond Osborn wrote:</p>
<blockquote type=3D"cite" style=3D"padding: 0 0.4em; border-left: #1010ff 2=
px solid; margin: 0"><!-- html ignored --><!-- head ignored --><!-- meta ig=
nored -->I added a call to QtWidgets.QApplication.instance().processEv=
ents() in order to force adjustResize() to work when switching tabs (that's=
another story). It succeeded in fixing my resize issue, but now it trigger=
s a segfault when I exit the application. This seemed to be related to the =
bug described in <a href=3D"https://www.riverbankcomputing.com/static/=
Docs/PyQt5/gotchas.html#crashes-on-exit">https://www.riverbankcomputing.com=
/static/Docs/PyQt5/gotchas.html#crashes-on-exit</a>. One fix, suggested by =
@ekhumoro on stackoverflow (<a href=3D"https://stackoverflow.com/questions/=
59120337/why-does-pyqt-sometimes-crash-on-exit">https://stackoverflow.com/q=
uestions/59120337/why-does-pyqt-sometimes-crash-on-exit</a>) was to delete =
the main window and the app first, but that doesn't seem to fix it. I am ru=
nning PyQt 5.12 because that is the last version supported by conda, so I c=
an't test the one-exit fix in v5.13, and my users probably wouldn't have it=
installed anyway. It happens on Macs and linux.
<div> </div>
<div>What I am asking is if there are additional things to try in addition =
to @ekhumoro's suggestion? Basically he suggests doing something like:</div=
>
<div> </div>
<div>
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r: var(--black-750);">show</span><span class=3D"pun" style=3D"margin: 0px; =
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it; font-stretch: inherit; line-height: inherit; vertical-align: baseline; =
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style=3D"margin: 0px; padding: 0px; border: 0px; font-family: inherit; font=
-style: inherit; font-variant-caps: inherit; font-stretch: inherit; line-he=
ight: inherit; vertical-align: baseline; box-sizing: inherit; color: var(--=
black-750);">exec_</span><span class=3D"pun" style=3D"margin: 0px; padding:=
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0px; font-family: inherit; font-style: inherit; font-variant-caps: inherit;=
font-stretch: inherit; line-height: inherit; vertical-align: baseline; box=
-sizing: inherit; color: var(--black-400);"># ensure correct deletion order=
</span><span class=3D"pln" style=3D"margin: 0px; padding: 0px; border: 0px;=
font-family: inherit; font-style: inherit; font-variant-caps: inherit; fon=
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ing: inherit; color: var(--black-750);">
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font-stretch: inherit; line-height: inherit; vertical-align: baseline; box=
-sizing: inherit; color: var(--blue-800);">del</span><span class=3D"pln" st=
yle=3D"margin: 0px; padding: 0px; border: 0px; font-family: inherit; font-s=
tyle: inherit; font-variant-caps: inherit; font-stretch: inherit; line-heig=
ht: inherit; vertical-align: baseline; box-sizing: inherit; color: var(--bl=
ack-750);"> main_window</span><span class=3D"pun" style=3D"margin: 0px; pad=
ding: 0px; border: 0px; font-family: inherit; font-style: inherit; font-var=
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inherit; line-height: inherit; vertical-align: baseline; box-sizing: inheri=
t; color: var(--black-750);"> app</span></code></pre>
<div>Does anyone understand why the crash only occurs if I have calls to pr=
ocessEvents() in the code? It never happens when I remove them.</div>
</div>
<div> </div>
<div>Thanks,</div>
<div>Ray</div>
<div> </div>
<div> </div>
</blockquote>
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