Streaming Behavior Changed

[Shawnyg]

Reproduction Steps
The streaming behavior for StreamingEnabled has unexpectedly changed. In a remote function call where the client invokes the server, if the server returns a newly created part, the client sees it as nil. This was not always the behavior and it seems that it only started today. In the repro file, press Play in studio and wait 2 seconds. In the output, it should print the part name, instead it prints nil. For our game, we relied on the prior behavior in certain instances.

Repro FIle.rbxl (33.4 KB)

Expected Behavior
The client should be able to access the returned part, more specifically since the part is within streaming radius of the client.

Actual Behavior
The client sees it as nil instead of returning the part’s name.

Issue Area: Engine
Issue Type: Other
Impact: High
Frequency: Constantly
Date First Experienced: 2022-03-01 00:03:00 (-05:00)
Date Last Experienced: 2022-03-01 00:03:00 (-05:00)

[CorvusCoraxx]

Thanks for the report and repro place. I’ve turned off a change that was enabled today, please let me know if the issue is resolved for you now. We will investigate the issue.

[Shawnyg]

Appreciate the quick resolution! Works great. FWIW, if it helps performance I’m more than fine with the change in the future if advanced notice is given! You’re the best.

[CorvusCoraxx]

FYI we are planning to go forward with this change so you will need to work around this behavior change:

Changes to PartInstance Streaming with Streaming Enabled

We will be soon rolling out a change to Streaming Enabled that improves how we stream parts that are grouped together into mechanisms and assemblies, such as vehicles and character models. With traditional streaming, a part connected to other parts via constraints could be sent independently of the connected parts, resulting in incomplete physics assemblies on the client. For example, the tire of a car that is closer to the player could be sent before the chassis and the rest of the car. Or lim…