Instant Desync on connect after 2 hours of multiplayer

skoapie commented 7 months ago

Describe the bug

What happened: Desync,
What were your doing right before this happened?: placing a bakery

Logs only have my own (host) LogOutput-copy.log

To Reproduce

Download Multiplayer - Demelza (15).txt
rename the file "Multiplayer.-.Demelza.15.txt" to "Multiplayer - Demelza (15).timber"
Make a folder named 'Multiplayer - Demelza' in the saves folder of Timberborn and save the file there.
Play the savegame and let someone connect and wait a minute or click on 1x speed and after seconds or a minute u will get a desync, perhaps place a building down to trigger it.

Screenshots Firstly, your mod is really cool man! Thanks for it! Through the playthrough we had some desync issues but not a huge problem until +- 2 hours in the game that we always desynced on connect, even thought we didn't do anything. i suspect for the beavers not being able to reach power shafts it caused an issue somehow. (in the save i had already deleted those) timberborn-shafts

Desktop (please complete the following information for both Host and Client):

OS: Windows 10
Timberborn version: 0.5.9.1-33dabbc-sw i think (played yesterday)
BeaverBuddies version: current (downloaded yesterday)

thomaswp commented 7 months ago

Thanks for working to make this reproducible! I'll take a look and see if I can confirm why things are desyncing. If you're right, it could be something pretty simple to fix.

thomaswp commented 7 months ago

Ok, I was able to reproduce the issue, No immediate red flags, so it'll take me some time to diagnose. I did also get a crash related to beaver swimming animations that I'll try to reproduce - may be related, since I see some construction there? Not sure. It's possible it's the same as #7 and I'm just misunderstanding the cause. I'll keep you posted. Glad you've enjoyed it and sorry you're at a dead end right now :/

skoapie commented 7 months ago

Interesting that the bug could be of of the beavers swimming, I had no clue.

Thank you for taking your free time to work on this man! Any way I could buy you a coffee?

skoapie commented 7 months ago

Ps want me to make a port forwarding guide for windows specific to timberborn? Would probably be helpful for players who don’t know anything about tech

thomaswp commented 7 months ago

A port forwarding guide would be a great way to say thank you. Maybe put it in a gist and I can add it to the wiki? I don't think they support PRs.

skoapie commented 7 months ago

Ah yeah i did some research but the only thing specific to Timberborn would be the Windows Firewall part but Timberborn already has the ports opened, it really depends on which router you use what kind of guide you would use.

skoapie commented 7 months ago

Here is the gist tho: https://gist.github.com/skoapie/851e46e7bb961f57237327b5646762e4

thomaswp commented 6 months ago

Thanks - added! Also, I know this conversation has gotten a bit sidetracked from your original issue. I'm still trying to isolate a fix. I've tried removing randomness, parallel ticking and other things and it's still happening, so I'm not sure what's going on.

thomaswp commented 6 months ago

Hey! I think I may have found the source of your desync (or at least one of them). I'm testing it under a few conditions to see how robust it is, but hopefully will have a fix out this weekend! Fingers crossed it works out.

skoapie commented 6 months ago

That's awesome man! I'm really curious as to what the problem was.

thomaswp commented 6 months ago

Alright, the fix is live (though probably needs more testing). Could you try v1.15-beta and see if it fixes your issue. Seems to for me. If not, let me know if it happens on the same save or a different one.

For your curiosity... there were actually two issues that each independently caused the desync by making trees and other reproducing living things desync:

The first was that the game getting a random index of a HasSet, and the index order of a HashSet isn't well defined, so I'm pretty sure that was causing some issues.
The second and more important is that the game actually does some random stuff while loading the save, which I was not expecting. So before the Client can connect and sync up it's random seed, it set some tree's death timers, which we don't experience until much later in a save. Hopefully not the games will both start loading from a fixed seed (this should also help with reproducing errors - they should happen at the same time each time you load a game, I hope).

skoapie commented 6 months ago

That second bug looks like a horror to debug, oh my. Glad you found it, we will test it tonight and i'll let you know what the results are :)

thomaswp commented 6 months ago

@skoapie have you encountered the bug again? I fixed one issue for sure, but I've realized there's a separate desync issue affecting another map I've tested on.

thomaswp commented 4 months ago

Good news all - I think I've figured out a primary cause of the desyncs and have a fix in the works. I'll need some time to test and polish it, but it seems to work on the maps you sent.

thomaswp commented 3 months ago

Hey, I've recently fixed a number of desync issues in v1.1.8, including the ones I observed in this tread. Please update BeaverBuddies, and if the problem persists, please upload your save file again so I can replicate it. I'm going to mark this as closed for now, but please reopen it the problem persists!

skoapie commented 3 months ago

Hey thomas, amazing work! Sadly we dont play the game anymore so i cant test it

thomaswp / BeaverBuddies

Instant Desync on connect after 2 hours of multiplayer #10