touch-packages team mailing list archive

[Antonis Kanouras <antonis+launchpad@xxxxxxxxxxxx>]

Re: the impact, I guess it affects users on laptops that regularly
(dis)connect external screens (eg. using same laptop at work & home or
connecting the laptop to a TV to watch a movie) without shutting down
the machine. From the few (<10) Kubuntu 15.04 installations I can be
blamed for, I'm the only one who noticed the bug even though I managed
to reproduce it on all of them.

Anyway, after reading the qtbugs and trying to cherry-pick a few
relevant upstream commits, I think Qt 5.4.1 is a lost cause for this bug
at this point, so feel free to postpone/cancel this SRU.

As my next steps, I'll try Fedora, and also 5.4.2 & 5.5 on Vivid & Wily
to see if I can reproduce it. Will take a few days however. :/

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to qtdeclarative-opensource-
src in Ubuntu.
https://bugs.launchpad.net/bugs/1450137

Title:
  Qt5 applications crash when switching screens

Status in qtdeclarative-opensource-src package in Ubuntu:
  Incomplete
Status in qtdeclarative-opensource-src source package in Vivid:
  Confirmed
Status in qtdeclarative-opensource-src source package in Wily:
  Incomplete

Bug description:
  # Impact
  When switching screens (e. g. when putting the laptop onto the docking station the notebook screen is turned off and the external one is turned on) Qt5 applications (including plasmashell) quite often crash.

  # Test Case
  * Have two screens. One plugged-in one not
  * Run plasma 5
  * Plug-in second screen and wait 10 seconds
  * Unplug and wait 10 seconds
  * Plug-in and wait 10 seconds
  * Unplug and wait 10 seconds
  * ...

  # Regression Potential
  Worst case scenario an application using qquickscreen would slow down because of erroneous screen change singals being emitted too often per second. This would however only reveal a lower level issue in the foundations that ultimately needs to be fixed anyway. 

  # Other Info
  The upstream code review [1] explains the issue and solution pretty well.

  https://codereview.qt-project.org/#/c/111100/

  
  --------- original report ---------------

  When switching screens (e. g. when putting the laptop onto the docking
  station the notebook screen is turned off and the external one is
  turned on) Qt5 applications (including plasmashell) quite often crash.
  This makes my laptop unusable, since I do that very frequently.

  The problem has already been described here: https://bugs.kde.org/show_bug.cgi?id=341497
  Apparently it is fixed in Qt 5.5

  I am running Kubuntu 15.04 64bit and libqt5gui5 5.4.1+dfsg-2ubuntu4.

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