QGis crashes when moving border between map canvas and overview map and "use render caching..." enabled

[kivih1]

when there are layers in the project and one or more layers is visible, and the Overview map is visible and docked (left or right), QGis crashes when trying to move the border between the canvas and the overview map. It is not necessary to have layers associated with the overview map for the program to crash.

[jef]

no reproducable with r12663 here.

[lutra]

Tested under linux and windows, both with qgis 1.4 and trunk, overview window docked on both sides. Not reproducable here.

[kivih1]

this is strange: I can't reproduce it on my computer at work, but it's still there on my private computer (which is only 3 months old). Maybe it has to do with the graphica card? Anyway, the very same project loaded in Qgis 1.3 behaves OK, whereas it crashes in 1.4. I will do some more experimentation in the coming weeks, and will report when I have any news.

Hubert

[lutra]

Hi, it would be great to see what the console returns when qgis crashes. Do you have any linux installation in your pc?

[kivih1]

Additional information added to the error report

[kivih1]

error signature

[kivih1]

Exception information

[kivih1]

Lutra,

I don't have Linux on my PC. This is what info I get from Windows after the crash:

Error signature: see jpg in the appendix Exception information (the first part of it, too large to show all): see jpg Additional information added to the error report: see txt

It all makes no sense to me but I hope it does so to you!

Hubert

[lutra]

Still not able to replicate this on both windows (xp) and linux. Can you replicate the problem on more than one machine, in order to rule out local configuration problems?

[kivih1]

I found out that Qgis only crashes when Actions->Options->Use cache when rendering is turned ON. When OFF no problems.

Hubert

[lutra]

Ok, this is confirmed also under linux.

Terminal says

"Warning: QPaintDevice: Cannot destroy paint device that is being painted
Segmentation fault"

[jef]

might be related to #2714.

[lutra]

Replying to jef:

might be related to #2714.

if the workaround for #2714 has fixed it then it does not work for this bug. It is pretty easy to reproduce on trunk but I also found vectors that do not cause qgis to crash.

[Alister]

Replying to lutra:

Replying to jef:

might be related to #2714.

if the workaround for #2714 has fixed it then it does not work for this bug. It is pretty easy to reproduce on trunk but I also found vectors that do not cause qgis to crash.

I've just installed 1.5 and am unable to reproduce. N.B. that for me 1.4 only crashed sometimes - not every time I moved the border.

[brushtyler]

Unable to reproduce it using QGis trunk (r13958) on Ubuntu 9.04

[lutra]

Replying to brushtyler:

Unable to reproduce it using QGis trunk (r13958) on Ubuntu 9.04

Hi Giuseppe,

it is not replicable with all vectors. I also found vectors that do not cause the crash.

[brushtyler]

Replying to lutra:

Replying to brushtyler:

Unable to reproduce it using QGis trunk (r13958) on Ubuntu 9.04

Hi Giuseppe, it is not replicable with all vectors. I also found vectors that do not cause the crash.

I tried more than one vector but nothing.

Could you attach a vector file which may cause the crash?

[lutra]

With this

 http://www.iambiente.pt/atlas/dl/regista_dl.jsp?zona=continente&grupo=&tema=c_curvasnivel

for me is instant crash even with "Use cache when rendering" OFF.

I'm using qgis 1.5 under Ubuntu 10.04

gio@sibirica:~$ qgis
Python support ENABLED :-) 
Loaded : GdalTools (package: GdalTools)
Warning: QHttp: empty path requested is invalid -- using '/'
Loaded : Plugin Installer (package: plugin_installer)
Loaded : fTools (package: fTools)
Loaded : OpenStreetMap plugin (package: osm)
Loaded : MapServer Export (package: mapserver_export)
gio@sibirica:~$ qgis
Python support ENABLED :-) 
Loaded : GdalTools (package: GdalTools)
Warning: QHttp: empty path requested is invalid -- using '/'
Loaded : Plugin Installer (package: plugin_installer)
Loaded : fTools (package: fTools)
Loaded : OpenStreetMap plugin (package: osm)
Loaded : MapServer Export (package: mapserver_export)
Warning: QPixmap::operator=: Cannot assign to pixmap during painting
Warning: QPainter::begin: A paint device can only be painted by one painter at a time.
Warning: QPainter::end: Painter not active, aborted
Warning: QPixmap::operator=: Cannot assign to pixmap during painting
Warning: QPainter::begin: A paint device can only be painted by one painter at a time.
Warning: QPainter::end: Painter not active, aborted
Warning: QPixmap::operator=: Cannot assign to pixmap during painting
Warning: QPainter::begin: A paint device can only be painted by one painter at a time.
Warning: QPainter::end: Painter not active, aborted
Warning: QPixmap::operator=: Cannot assign to pixmap during painting
Warning: QPainter::begin: A paint device can only be painted by one painter at a time.
Warning: QPainter::end: Painter not active, aborted
Warning: QPixmap::operator=: Cannot assign to pixmap during painting
Warning: QPainter::begin: A paint device can only be painted by one painter at a time.
Warning: QPainter::end: Painter not active, aborted
Segmentation fault

[brushtyler]

Ok, now I'm able to reproduce it too (QGis trunk r13958 on Ubuntu 9.04)

[brushtyler]

Replying to lutra:

With this  http://www.iambiente.pt/atlas/dl/regista_dl.jsp?zona=continente&grupo=&tema=c_curvasnivel for me is instant crash even with "Use cache when rendering" OFF.

For me only if the cache render is enabled.

Before crash, the terminal displays this message:

"Warning: QPaintDevice: Cannot destroy paint device that is being painted
Segmentation fault"

This message is displayed from

/home/brushtyler/Projects/Work/Faunalia/qgis/qgis_unstable/src/core/qgsmaplayer.cpp: 848

delete mpCacheImage;

So I think that when the render is disabled the crash is related to a different issue.

[pcav]

Might be due to Qt? Could you please try again with current trunk, and report which Qt version you use?

[lutra]

tested again with trunk, on ubuntu 10.04 and 10.10 (different libqt4 versions), render caching on and off and it is always instant crash.

[brushtyler]

Replying to lutra:

tested again with trunk, on ubuntu 10.04 and 10.10 (different libqt4 versions), render caching on and off and it is always instant crash.

I made further tests. I found that segfault is dued to the processEvent() calls in QgsVectorLayer? (QgsVectorLayer.cpp:1045).

Searching for similar Qt bugs, I found #2714 (maybe the same bug??), and also Martin wrote the problem is caused by processEvent(). The crash happens in Qt libraries.

I discovered another piece, it's caused by an invalid extra-call. If I add debug messages both before (QgsVectorLayer.cpp:1039) and after (QgsVectorLayer.cpp:1055) the qapp->processEvent() call I notice that there are N pre-call messages and N+1 post-call messages.

[brushtyler]

Replying to brushtyler:

I discovered another piece, it's caused by an invalid extra-call. If I add debug messages both before (QgsVectorLayer.cpp:1039) and after (QgsVectorLayer.cpp:1055) the qapp->processEvent() call I notice that there are N pre-call messages and N+1 post-call messages.

Found, no extra-call (would be very strange!), but it's a race condition, see the attachment.

[brushtyler]

Debug messages and Backtrace

[brushtyler]

Look at the attachment qgis_ticket_2339_bt:

at line 95 you can see the missing "before qApp->processEvents()"

and after a refreshing of the layer

at line 189 there's the related "after qApp->processEvents()"

[jef]

duplicate of #2714.