Limit outgoing to_device EDU size to 65536#18416
Merged
MadLittleMods merged 57 commits intoelement-hq:developfrom Mar 24, 2026
Merged
Limit outgoing to_device EDU size to 65536#18416MadLittleMods merged 57 commits intoelement-hq:developfrom
MadLittleMods merged 57 commits intoelement-hq:developfrom
Conversation
MadLittleMods
changed the title
MadLittleMods
added a commit
that referenced
this pull request
Jun 19, 2025
From my review of #18416
Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
Contributor
|
Looks like the CI tests are flaky as mentioned here : #18537 |
Contributor
|
Not able to reproduce the issue here by running |
synapse/handlers/devicemessage.py
Outdated
Comment on lines
+451
to
+455
| if len(current_edu_content["messages"]) == 0: | ||
| raise EventSizeError( | ||
| f"device message to {recipient} too large to fit in a single EDU", | ||
| unpersistable=True, | ||
| ) |
Contributor
There was a problem hiding this comment.
We should link it in the code here
Contributor
Author
I am not sure what you meant here, and for whatever reason I can't comment in the thread. |
Contributor
|
Relevant thread is here: #18416 (comment) (press 'load more' when viewing the conversations to get everything visible) We should link your spec PR in the code where we raise |
Contributor
Author
Thank you stupid GH for this great view of a comment with no context and no way to easily reach the context :)
Thanks for the direct link, MadLittleMods >> GitHub. |
MadLittleMods
approved these changes
Mar 23, 2026
Contributor
MadLittleMods
left a comment
MadLittleMods
left a comment
There was a problem hiding this comment.
Looks good. I'm unable to apply the last edits
Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
Contributor
|
Thanks for the fix @MatMaul 🐏 |
Contributor
Author
|
We did it! Thanks for the reviews 🙏 |
MadLittleMods
added a commit
that referenced
this pull request
Mar 24, 2026
Spawning from #18416 (comment)
3 tasks
MadLittleMods
added a commit
that referenced
this pull request
Mar 25, 2026
…clock) (#19602) Spawning from #18416 (comment)
erikjohnston
added a commit
that referenced
this pull request
Mar 27, 2026
This reverts commit 7fad50f.
erikjohnston
added a commit
that referenced
this pull request
Mar 27, 2026
Reverts #18416 Unfortunately, this causes failures on `/sendToDevice` endpoint in normal circumstances. If a single user has, say, a hundred devices then we easily go over the limit. This blocks message sending entirely in encrypted rooms. cc @MadLittleMods @MatMaul
erikjohnston
pushed a commit
that referenced
this pull request
Mar 27, 2026
If a set of messages exceeds this limit, the messages are split across several EDUs. Fix #17035 (should) There is currently [no official specced limit for EDUs](matrix-org/matrix-spec#807), but the consensus seems to be that it would be useful to have one to avoid this bug by bounding the transaction size. As a side effect it also limits the size of a single to-device message to a bit less than 65536. This should probably be added to the spec similarly to the [message size limit.](https://spec.matrix.org/v1.14/client-server-api/#size-limits) Spec PR: matrix-org/matrix-spec#2340 --------- Co-authored-by: mcalinghee <mcalinghee.dev@gmail.com> Co-authored-by: Eric Eastwood <madlittlemods@gmail.com>
erikjohnston
added a commit
that referenced
this pull request
Mar 27, 2026
This is based on #18416, which got reverted due to it rejecting to-device messages to users with many devices. The main change here is that if a to-device EDU for a single user is too large, then we split it up into multiple EDUs.
erikjohnston
added a commit
that referenced
this pull request
Mar 27, 2026
This is based on #18416, which got reverted due to it rejecting to-device messages to users with many devices. The main change here is that if a to-device EDU for a single user is too large, then we split it up into multiple EDUs.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
5 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
If a set of messages exceeds this limit, the messages are split across several EDUs.
Fix #17035 (should)
There is currently no official specced limit for EDUs, but the consensus seems to be that it would be useful to have one to avoid this bug by bounding the transaction size.
As a side effect it also limits the size of a single to-device message to a bit less than 65536.
This should probably be added to the spec similarly to the message size limit..
Spec PR: matrix-org/matrix-spec#2340
Pull Request Checklist