[BUG] diff-dom freezing on CMS content refresh

[petrklus]

Description

We are experiencing issues with the CMS refresh. For certail plugin configurations and post-plugin modification, the browser tab first freezes, later to crash due to out of memory error. We have confirmed the same on Google Chrome / Mozilla Firefox.

Steps to reproduce

1. Trigger content/structure board refresh
2. Tab crashes

Expected behaviour

The page content to update.

Actual behaviour

The diff between incoming document and actual document freezes up:

https://github.com/django-cms/django-cms/blob/develop/cms/static/cms/js/modules/cms.structureboard.js#L1291

Only tab restart fixes the issue.

Screenshots

Additional information (CMS/Python/Django versions)

Django CMS 3.11.0 or 1, Django 3.2.

Tested on Mozilla Firefox and Google Chrome

Do you want to help fix this issue?

We have looked into this further and the issue seems to be down to DiffDOM version 2.5.1. We have tried upgrading to the latest version 4.2.8, which works in debug mode, however, is not compatible with the current UglifyJS config.

• Yes, I want to help fix this issue and I will join #workgroup-pr-review on Slack to confirm with the community that a PR is welcome.
• No, I only want to report the issue.

[Rogell]

This issue happened to me also and I can confirm that upgrading to the latest DiffDOM (version 5.0.4) fixes the problem. Works with debug mode on and off. UglifyJS doesn't throw any warnings regarding DiffDOM.
I will not create a pull request as I don't have time to read all contribution requirements so if anyone wants to fix it here are my changes.

Details:
Branch: release/3.11.x
Python version: 3.11
NPM version: 6.14.4
System: Ubuntu 20.04.2 LTS on WSL2
Django: 3.2

Changes:
package.json:52 -> "diff-dom": "5.0.4",
cms/static/cms/js/modules/cms.structureboard.js:11 -> import { DiffDOM } from 'diff-dom';

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[petrklus]

@fsbraun would you know of anyone with the CMS editor code experience who can look into this?

[marksweb]

@petrklus whats happening with the plugins that might give us a clue on how to reproduce this?

[fsbraun]

@petrklus Can you reopen #7461 ? So far, I have not been able to make the tests pass with the updated diffdom dependency. OK, I just realized, I could reopen it myself.

[fsbraun]

@petrklus I think I have a solution (#7599) for v4:

• ChromeHeadless (using puppeteer) instead of PhantomJS
• (What kept me from succeeding at first were insufficient viewport dimensions in ChromeHeadless.)
• Update of karma

Do you think you can transfer the changes of #7599 to #7461 to see if we get tests running?

[DmytroLitvinov]

Hey @fsbraun ,
We struggled in our project with the same issue:

• DjangoCMS 3.11.3
• Django 3.2

After swapping to develop version in our staging, we see there is no issue.
(In develop branch there is such commit d8e9c52

Helpful links:

• Compare changes between branches 3.11.3 and develop
• fix: add updates same as PR: #7599

Do you think we can release new minor version of DjangoCMS like 3.11.4 with such fix? I am ready to provide help here with a contribution and I am really would be glad to do that.

[fsbraun]

I am literally working on it at the moment :-)

[fsbraun]

@DmytroLitvinov Out now!

[DmytroLitvinov]

Wow. Thank you 🤩
Going to deploy it to staging and production new minor version.

[fsbraun]

One after the other!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[fsbraun]

Fixed in django CMS version 3.11.4