Calibre UI freezes periodically

Geremia · 11-17-2025, 10:11 PM

Calibre's user-interface (UI) freezes periodically. I also run the web server.

What log(s) can I view to figure out why the UI freezes?

I have to send "SIGKILL" to the 3 Calibre processes:

Code:

44636 ?        Ssl    0:18 /opt/calibre/bin/calibre --detach
44639 ?        S      0:00 /opt/calibre/bin/calibre-parallel --pipe-worker from calibre.utils.safe_atexit import main; main()
44718 ?        S      0:00 /opt/calibre/bin/calibre-parallel --pipe-worker from calibre.utils.ipc.pool import run_main, worker_main; run_main(61, worker_main)

and restart calibre every-time the UI freezes.

theducks · 11-17-2025, 10:17 PM

Is this a REPO version install or the commandline from the Calibre site?
(Hint: Pick #2)
Also, Is the Library folder on a Local attached drive?

kovidgoyal · 11-17-2025, 11:48 PM

If the UI is freezing calibre logs wont help you since the frozen process is the one that would be doing the logging. You dont say anything about your system, but if I had to gues sits likely a wayland compositor issue. Try running under X11 instead.

Geremia · 11-18-2025, 11:46 PM

Quote:

Originally Posted by theducks

Is this a REPO version install or the commandline from the Calibre site?

https://download.calibre-ebook.com/8...4.0-x86_64.txz

Quote:

Originally Posted by theducks

Is the Library folder on a Local attached drive?

Internal SSD drive (BTRFS).

Quote:

Originally Posted by kovidgoyal

Try running under X11 instead.

That's what I'm using.
Slackware64-current with KDE Plasma 5.27.12 and Nvidia proprietary graphics card drivers.

kovidgoyal · Yesterday, 12:12 AM

Then debug systematically. Run calibre without the server nd see if the freeze occurs. If it doesnt then look at the server logs to see what operation in the server is cauing the freeze. If it does then run calibre without third party plugins and see if it occurs, if it doesnt then eliminate the plugins one by one to find th eculprit. Then run calibre without config and so on.

theducks · Yesterday, 10:23 AM

Quote:

Originally Posted by Geremia

https://download.calibre-ebook.com/8...4.0-x86_64.txz
Internal SSD drive (BTRFS).That's what I'm using.
Slackware64-current with KDE Plasma 5.27.12 and Nvidia proprietary graphics card drivers.

Thanks.
I see the master has answered based on your answers

11-17-2025, 10:11 PM	#1
Geremia Addict Posts: 265 Karma: 100000 Join Date: Oct 2012 Device: Calibre	Calibre UI freezes periodically Calibre's user-interface (UI) freezes periodically. I also run the web server. What log(s) can I view to figure out why the UI freezes? I have to send "SIGKILL" to the 3 Calibre processes: Code: 44636 ? Ssl 0:18 /opt/calibre/bin/calibre --detach 44639 ? S 0:00 /opt/calibre/bin/calibre-parallel --pipe-worker from calibre.utils.safe_atexit import main; main() 44718 ? S 0:00 /opt/calibre/bin/calibre-parallel --pipe-worker from calibre.utils.ipc.pool import run_main, worker_main; run_main(61, worker_main) and restart calibre every-time the UI freezes. Last edited by Geremia; 11-17-2025 at 10:15 PM.

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11-17-2025, 10:17 PM	#2
theducks Well trained by Cats Posts: 31,286 Karma: 62000000 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Is this a REPO version install or the commandline from the Calibre site? (Hint: Pick #2) Also, Is the Library folder on a Local attached drive?

11-17-2025, 11:48 PM	#3
kovidgoyal creator of calibre Posts: 45,634 Karma: 28549046 Join Date: Oct 2006 Location: Mumbai, India Device: Various	If the UI is freezing calibre logs wont help you since the frozen process is the one that would be doing the logging. You dont say anything about your system, but if I had to gues sits likely a wayland compositor issue. Try running under X11 instead.

Yesterday, 12:12 AM	#5
kovidgoyal creator of calibre Posts: 45,634 Karma: 28549046 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Then debug systematically. Run calibre without the server nd see if the freeze occurs. If it doesnt then look at the server logs to see what operation in the server is cauing the freeze. If it does then run calibre without third party plugins and see if it occurs, if it doesnt then eliminate the plugins one by one to find th eculprit. Then run calibre without config and so on.