To-device messages delayed by _DestinationWakeupQueue

[richvdh]

Description

#12132 introduced functionality to spread out the federation transmission requests due to device-list updates. However it also applies to to-device messages (due to the default immediate=False at https://github.com/matrix-org/synapse/pull/12132/files#diff-4db75239ae91da3be91b6ccacb4dc969be778e832da2976b9b8fd628f16e6b52R674) which doesn't appear to have been the intention, and can cause significant delays in transmission of to-device messages.

Steps to reproduce

• log in on a new device
• soon after, send an E2E message
• express sadness at how long the keys take to turn up.

Homeserver

sw1v.org

Synapse Version

{"server_version":"1.77.0 (b=HEAD,t=v1.77.0,3e90dfdd8)","python_version":"3.7.3"}

Installation Method

Docker (matrixdotorg/synapse)

Database

postgres

Workers

Single process

Platform

debian somethingsomething

Configuration

experimental_features:
  msc3958_supress_edit_notifs: True

Relevant log output

Adjacent federation transmissions to element.io:

2023-02-23 13:31:47,814 - synapse.federation.sender.transaction_manager - 127 - INFO - federation_transaction_transmission_loop-97225 - TX [element.io] {1676822929244} Sending transaction [1676822929244], (PDUs: 1, EDUs: 2)
2023-02-23 13:31:48,277 - synapse.http.matrixfederationclient - 308 - INFO - federation_transaction_transmission_loop-97225 - {PUT-O-2230172} [element.io] Completed request: 200 OK in 0.46 secs, got 60 bytes - PUT matrix://element.io/_matrix/federation/v1/send/1676822929244
2023-02-23 13:31:48,277 - synapse.federation.sender.transaction_manager - 174 - INFO - federation_transaction_transmission_loop-97225 - TX [element.io] {1676822929244} got 200 response
2023-02-23 13:36:22,721 - synapse.federation.sender.transaction_manager - 127 - INFO - federation_transaction_transmission_loop-101748 - TX [element.io] {1676822931004} Sending transaction [1676822931004], (PDUs: 0, EDUs: 94)
2023-02-23 13:36:26,499 - synapse.http.matrixfederationclient - 308 - INFO - federation_transaction_transmission_loop-101748 - {PUT-O-2233711} [element.io] Completed request: 200 OK in 3.78 secs, got 11 bytes - PUT matrix://element.io/_matrix/federation/v1/send/1676822931004
2023-02-23 13:36:26,499 - synapse.federation.sender.transaction_manager - 174 - INFO - federation_transaction_transmission_loop-101748 - TX [element.io] {1676822931004} got 200 response

Anything else that would be useful to know?

No response

[richvdh]

see https://github.com/matrix-org/element-web-rageshakes/issues/20273 for an example of this

[H-Shay]

Could this be resolved by adding immediate=True to this call here?

[richvdh]

Could this be resolved by adding immediate=True to this call here?

I think that would fix this particular case, yes. But it looks to me as though the intention was that the default be immediate=True. @erikjohnston any opinions?

[erikjohnston]

Ah, yup. I very much thing I meant the default should be immediate=True

[H-Shay]

Right I can fix that then, will put up a PR.