1816237 - Thunderbird screen freezes frequently

Status: UNCONFIRMED

(Calendar :: General, defect)

Description

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/109.0

Steps to reproduce:

Configure Thunderbird with an IMAP account and a CalDAV/CardDAV account. (The IMAP accpunt is in the cloud, CalDAV/CardDAV is on a server in the same LAN, but that may not be relevant).

Start Thunderbird and use it normally: browse email, write messages, work with Tasks and Calendar

Actual results:

The application window frequently freezes and no longer responds to user input, then unfreezes after a while (I would estimate from 10 seconds up to at least a minute). These freezes happen unpredictably and frequently enough to be annoying.

While the screen is frozen, user input still seems to get processed: keyboard input becomes visible after the screen unfreezes; mouse clicks get handled by the control that should have been in this place – it looks like a redraw issue, while the internal state of windows and controls is updated correctly.

Suspecting this to have something to do with network transactions, I have indeed managed to provoke this issue by initiating something that would trigger a request to the CalDAV server, such as marking a task complete or starting synchronization. This causes the screen to freeze instantly for approximately a minute.

However, some of the freezes are seemingly random, so it may not be CalDAV/CardDAV alone.

The CalDAV/CardDAV server is not reachable when I am on the road (it is configured in the profile but the DNS name does not resolve), but I am still getting random freezes in both cases.

I am on Ubuntu MATE, with Thunderbird from the Ubuntu repos. It started after I upgraded from Ubuntu 20.04 to 22.04, around October 2022. I usually apply updates from the official repos within 24h (only kernel updates may take longer). I have noticed this behavior since at least Thunderbird 102.4.2, currently on 102.7.1.

Behavior seems similar to bug #1775032, but I am not sure if we are both seeing the exact same thing. I have asked for clarification there – if it turns out to be the same issue, feel free to close this as a dupe after copying all relevant information over.

This has also been reported to Ubuntu MATE as https://bugs.launchpad.net/ubuntu-mate/+bug/2000415.

Expected results:

Everything works normally; screen responds to user input and redraws accordingly

Comment 1

[Wayne Mery (:wsmwk)]

Are you seeing Bug 1849540 - Thunderbird freezes when adding CalDAV calendar with VTIMEZONE ?

Comment 2

[Michael von Glasow]

I am not seeing the freezing behavior described in that ticket (TB freezes indefinitely with CPU at 100%). CPU seems to be at less than 100% as far as I can tell, and Thunderbird so far has recovered every time.

However, I cannot tell for sure whether I have calendar entries with VTIMEZONE. I do see, however, Thunderbird freezing reproducibly for around 30 seconds with high CPU load (oscillating, seldom reaching 100%) when I switch to the calendar tab and switch months/years.

Comment 3

[Wayne Mery (:wsmwk)]

When using version 128, does this still reproduce for you?

Comment 4

[Michael von Glasow]

It might take me some time to test that. Ubuntu 22.04 (which I use) still has 115, don’t know when they’ll offer the 24.04 upgrade to LTS users. As soon as I’m on 128+, I’ll let you know. If anyone else has a chance to test this in the meantime, feel free.

Comment 5

[Michael von Glasow]

Re Ubuntu upgrades, the 24.04 rollout is taking longer due to issues with the upgrade tool, see https://askubuntu.com/questions/1525863/do-release-upgrade-from-22-04-lts-to-24-04-lts-still-no-update-available

Comment 6

[Michael von Glasow]

Finally managed to upgrade to Ubuntu 24.04, which now has Thunderbird via snap, currently at 128.4.1esr. I briefly tested the issue by scrolling though the months in Calendar. There is still some delay (~1–2 seconds), but a lot more responsive than it was before.

Comment 7

[Michael von Glasow]

After some more testing, including editing tasks, I notice that the delay is significantly shorter (up to ~10–15 seconds), but it is still there.

I strongly recommend getting any and all network operations off the UI thread. (Android even enforces that on its apps; any app targeting a recent version of Android will get killed by the OS as soon as the UI thread initiates a network operation.) It does make the code slightly more complex, but it improves responsiveness of the UI.

Comment 8

[Wayne Mery (:wsmwk)]

Thanks Michael.

Is offline enabled or disabled for the calendar?
If disabled, then this should be helped by Bug 1933099 - Importing many items from a CalDAV server with "Offline Support" disabled can cause significant jank