Unanchored objects falling through the ground when server is under high loads

Bug Reports Engine Bugs
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#1

In Lumber Tycoon 2, some users report items falling through the ground and being lost when the server is under high stress: either when a large base is loading or when multiple large bases are loaded.

The frequency of this issue is low but the severity is high: most users play on healthy servers and don’t have huge bases, but when it happens it can be devastating for users.

I first received reports of this issue on Nov 16 2023.

I suspected that this may be related to PhysicsSteppingMethod, but I still received reports after changing it to Fixed.


3 Likes
#2

I find it incredible how Lumber Tycoon 2 supports so many objects with a considerably low amount of lag compared to what it “should” have.

1 Like
#4

We are looking into this issue. I know you said it only happens intermittently, but was wondering if you had an isolated repro by any chance :slight_smile:

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#5

Hello there! While waiting for a repro, I’ve gone ahead and reverted a potentially related change. Let me know if you still experience issues.

For context: We’ve recently added certain limits to the amount of physics work that can be added to the engine in order to prevent servers from hanging. This means these places have a LOT of parts (way cool!). The limit was set to a point where on average a single world step would take about 5 s (contrast to the normal 1/240 s for 4 physics steps per worldstep), which would eventually “deathspiral” into the server failing to keep up and leads to hangs. I believe however that the threshold is not entirely accurate, and may not be taking sleeping parts properly into account, for example. That’s my hypothesis, anyway.

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