[0.12.X] Desync if doing stuff with pipes

[Ringkeeper]

My wife and i play together in a local network. She is the host. Happens in all 0.12. versions so far, at the moment we have 0.12.29. Not playing via steam.

Sometimes / often we get desync loops while i do stuff with our power production, specially while building pipes for water. I have then to use alt+F4 to disconnect, she need to load an older save so we can go on with building.

Sometimes it happens if i connect pipes, sometimes just with mouse-over on anything that contains fluid, sometimes while replacing pipes etc.

Link to desync report: (16mb)
https://www.dropbox.com/s/m80nhxbmn979b ... 6.rar?dl=0

Link to factorio-current.log:
https://www.dropbox.com/s/qykw9gjx4yva0 ... t.log?dl=0

[Rseding91]

The first step is: can you reproduce the desync without the mods?

If not, then one of them would be causing it.

It's possible one of the mods is written in-correctly in how it handles logic making the game desync. If you could zip up and upload all of the mods I can take a quick glance at them to see if anything looks out of the normal.

[Ringkeeper]

sure, but its big

450 MB
https://www.dropbox.com/s/jo59u3tpekryx29/mods.rar?dl=0

We had this problem also without any mod that should handle fluids. So far i found the desync kinda reproductive with the "Obnisk" (Boiler from yuoki) and pipes "A2-Pipes" (yuoki) but also normal pipes and normal boilers can cause the problem (even not that often).

[Rseding91]

Try removing the mod "TrainOutpost". From what I'm seeing it's broken when it comes to multiplayer and determinism as it re-inits its own version of a random number generator every time you load the game. Loading the game happens for anyone connecting to another persons game so every peer in a multiplayer environment would potentially have a different random number generator in that mod.

If it did anything with those numbers (which it does) they would end up different for each peer and result in desyncs.

Now, why it does that I have no idea.. we provide "math.random()" which is deterministic across a save file and random based off the seed of the map being generated. That entire part of that mod should be removed and replaced with calls to math.random().

[Ringkeeper]

Trainoutpost is like RSO . It changes the way the ore is distributed on the map to encourage the use of trains. Will make a bug post at that mod Thanks for the help so far.

[SirRichie]

Try removing the mod "TrainOutpost". From what I'm seeing it's broken when it comes to multiplayer and determinism as it re-inits its own version of a random number generator every time you load the game. Loading the game happens for anyone connecting to another persons game so every peer in a multiplayer environment would potentially have a different random number generator in that mod.

If it did anything with those numbers (which it does) they would end up different for each peer and result in desyncs.

Now, why it does that I have no idea.. we provide "math.random()" which is deterministic across a save file and random based off the seed of the map being generated. That entire part of that mod should be removed and replaced with calls to math.random().

I am the author of TrainOutposts. The reason for the use of a custom RNG implementation rather than math.random() is that at the time of creation of this mod, math.random() was not MP-determinisitic yet

I have not received any reports that TrainOutposts is causing desyncs. Of course I cannot claim that it is absolutely bullet proof. From what you describe, it should happen pretty much anytime someone joins an MP game, which is definitely not true, I took care of that. Anyway, I am happy to help go bug hunting if someone needs my input.