Opened 3 weeks ago

Last modified 3 weeks ago

#32568 new defect

nextcloud collaborative "pad" synchronization breaks down with multiple users

Reported by: anarcat Owned by: nextcloud-admin@…
Priority: Medium Milestone:
Component: Internal Services/Service - nextcloud Version:
Severity: Normal Keywords:
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor:


Today, in both the metrics and vegas meetings, we had problems using the "nextcloud pad", that collaborative, WYSIWYG, "markdown" text editor. We're trying to use this as a replacement for Storm's Etherpad installation and it worked the last meeting.

But now we were over 12 people in the pad and it didn't work so well. The main problem is synchronization, e.g. one user would "strikethrough" some text but others wouldn't see the style change. This is particularly critical in Vegas meetings as we use that style information to carry information about how the meeting should proceed.

There are also issues scrolling around the content using cursor keys (e.g. pgdown jumps to the end of the document instead of one page down), but that's probably unrelated.

Child Tickets

Change History (6)

comment:1 Changed 3 weeks ago by sysrqb

As one datapoint, I open devtools on the page and whenever I modified the page I saw there was a xhr POST request initiated to Interestingly, it seems like they all timed out (which could explain the lack of synchronization across browsers). I don't know if that was simply a local issue, or if that was experienced by everyone using the pad, as well.

Currently, when I edit the document I see the same request initiated but now there is a "412: Precondition Failed" response.

comment:2 Changed 3 weeks ago by gaba

I think one problem is that we are using this app in right now:

and we should consider using a pad instead:

comment:3 Changed 3 weeks ago by gaba

It may be related to this bug in the text app:

comment:4 Changed 3 weeks ago by anarcat

i just had a quick chat with micah about this, and here's a summary...

for the sake of clarity, I'll start by naming things, because it's hard and i think a source of confusion:

  • onlyoffice: the Nextcloud collaborative editor with support for Word and Excel documents, kind of like Google docs (installed on nc.tpo)
  • etherpad app, ownpad: the Nextcloud Etherpad app that bridges Nextcloud with an existing Etherpad lite instance (not installed on nc.tpo)
  • markdown app, text app: the Nextcloud Text app that allows collaborative editing of text documents (installed on nc.tpo).

Let's take those one by one...

The text app

The Text app we are having problems with in the meetings is built on top of Prosemirror, one of *many* collaborative editors I have found in a previous research last year, and tiptap, a rich text editor built on top of Prosemirror. This app is fairly recent (june 2019) and shipws with NC 17 by default.

Micah told me the problems we are seeing are known, and others have suffered the same problems. He suspects the NC people haven't yet made the app scale to tens of users like we've seen in the vegas and metrics meetings (or at least, more than 10). This would confirm sysrqb's observations that it would fall apart under load. It works fine for a couple people, with some quirks, like a small scratch pad, but not so well for larger groups.

There might be performance tweaks we could do in Nginx or elsewhere to fix the issue sysrqb observed.

The etherpad app

This app is not yet installed on our instance, but could be. It was (or still is?) installed on but because Riseup's etherpad instance expires documents after a while, this led to data loss as the files disappeared from NC as well.

So while we could deploy that app in our instance, it might lead to the same problem as there's no obvious marker that a pad will be removed in the NC UI. There is, of course, a huge warning in the pad itself when you first open it, but people forget about this all the time.

If we use it only for ephemeral stuff like the vegas meeting notes, maybe that would be alright, but I would still be worried that people would use it for other things and lose data.

Maybe we could just use Riseup's pad service for our meetings? Do we absolutely need this to be integrated in Nextcloud? If so we would have three different collaborative editors in nextcloud, which doesn't seem very reasonable to me...

Alternatively, can't we just use meetbot to take minutes in meetings? :)

The onlyoffice app

We *could* use the OnlyOffice app for meetings. We haven't tried that in a large scale yet, as far as I know. It might have exactly the same problems as the text app, maybe even worse because onlyoffice is much heavier. It would be worth a try, however.


Known issue. Needs debugging or we could just use or meetbot or onlyoffice for meetings.

comment:5 Changed 3 weeks ago by anarcat

also, thanks gaba and sysrqb for the diagnostics, that's super useful! :) in particular, thanks gaba for the detective work in the text app issue queue. it sure looks like there's a race condition in the code that can get triggered when multiple people edit at the same time. and since they found it, there's a good chance *that* specific issue gets fixed...

so maybe this is just a matter of "wait and see" (ie. use for a bit longer) while they fix their things...

comment:6 Changed 3 weeks ago by gaba

Yes. I see the problem with using owncloud and may not be clear for people and we lose data that we do not want to lose.

I agree about moving any agenda/notes for meetings to and periodically archive them in if we want to save old notes. Once they fix the text app then we can consider if we move there or not. For now we can continue using as we use for network and anti-censorship team meetings.

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