Viewer frozen when opening EPUB

hgr · 12-28-2022, 03:01 PM

Yep, another one of these - after using 4.23 for a long time to manage my paltry library under (up-to-date) Opensuse Leap 15.4 I decided to switch to 6.10 - and guess what, when trying my epubs (more or less all of them) the viewer froze. Reverting back to 4.23 restored usability, but this was not quite satisfying.
So I got curious and tested the whole thing on my Mint 21.1 (also up-to-date) notebook and there everything worked like a charm with 6.10.
The first thing I found when investigating were a lot of references to Python and this looked a bit suspicious, because there was this switch to Python3 with Calibre 5 - and guess what again, the same symptom with the frozen viewer resurfaced after installation of Calibre 5 on the Leap box (and went away after reverting to 4.23). But Python3 is present properly on both machines, and I also checked the xdb libraries.
The last advice checked was Govid's hint to set the Qt environment variable off for acceleration (set QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu"; export QTWEBENGINE_CHROMIUM_FLAGS). This seems to solve the problem for the Leap 15.4 installation - maybe because this is a Nouveau setup?
Yes, the original problem is solved, I will continue my tests and research, anybody got an explanation about this Bermuda triangle of GPU, Python and Qt?

Quoth · 12-28-2022, 03:22 PM

OK here with Mint 20.1, Mate 1.24 and a custom theme
Calibre 6.10
Everything working all the time since I was on 19.1

JSWolf · 12-28-2022, 03:23 PM

Too many version of Linux with too many problems.

BetterRed · 12-28-2022, 05:48 PM

Quote:

Originally Posted by JSWolf

Too many version of Linux with too many problems.

Snakeoil on a Raspberry Pie

There are said to be about 600 Linux distros, that's 20 a year since 1992.

BR

theducks · 12-28-2022, 07:47 PM

Quote:

Originally Posted by BetterRed

Snakeoil on a Raspberry Pie

There are said to be about 600 Linux distros, that's 20 a year since 1992.

BR

<snark on> Linux distros are a bit like Jon. Do it my way. The plus, is they can. The minus is the poor developer like Kovid that is trying to make their app RUN. </snark off>

kovidgoyal · 12-28-2022, 10:09 PM

It has nothing to do with Python. Its simply an incompatibility between the GPU drivers and Qt WebEngine (which is wrapped chromium).

hgr · 12-30-2022, 05:43 AM

Quote:

Originally Posted by kovidgoyal

It has nothing to do with Python. Its simply an incompatibility between the GPU drivers and Qt WebEngine (which is wrapped chromium).

I concur. Just checked the Mint 21.1 setup, there is an Intel GPU (typical notebook stuff ...) using the i915 driver, and on that Leap 15.4 setup there is a Nvidia GTX 980 Ti using the Nouveau driver.

The interesting part here is that not only Nouveau seems to have issues with Qt Webengine ...

12-28-2022, 03:01 PM	#1
hgr Junior Member Posts: 2 Karma: 10 Join Date: Nov 2013 Device: Sony PRS T2	Viewer frozen when opening EPUB Yep, another one of these - after using 4.23 for a long time to manage my paltry library under (up-to-date) Opensuse Leap 15.4 I decided to switch to 6.10 - and guess what, when trying my epubs (more or less all of them) the viewer froze. Reverting back to 4.23 restored usability, but this was not quite satisfying. So I got curious and tested the whole thing on my Mint 21.1 (also up-to-date) notebook and there everything worked like a charm with 6.10. The first thing I found when investigating were a lot of references to Python and this looked a bit suspicious, because there was this switch to Python3 with Calibre 5 - and guess what again, the same symptom with the frozen viewer resurfaced after installation of Calibre 5 on the Leap box (and went away after reverting to 4.23). But Python3 is present properly on both machines, and I also checked the xdb libraries. The last advice checked was Govid's hint to set the Qt environment variable off for acceleration (set QTWEBENGINE_CHROMIUM_FLAGS="--disable-gpu"; export QTWEBENGINE_CHROMIUM_FLAGS). This seems to solve the problem for the Leap 15.4 installation - maybe because this is a Nouveau setup? Yes, the original problem is solved, I will continue my tests and research, anybody got an explanation about this Bermuda triangle of GPU, Python and Qt?

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12-28-2022, 03:22 PM	#2
Quoth Still reading Posts: 14,016 Karma: 105092227 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper	OK here with Mint 20.1, Mate 1.24 and a custom theme Calibre 6.10 Everything working all the time since I was on 19.1

12-28-2022, 03:23 PM	#3
JSWolf Resident Curmudgeon Posts: 79,745 Karma: 145864619 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Too many version of Linux with too many problems.

12-28-2022, 10:09 PM	#6
kovidgoyal creator of calibre Posts: 45,345 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	It has nothing to do with Python. Its simply an incompatibility between the GPU drivers and Qt WebEngine (which is wrapped chromium).

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