Rejoining multiplayer games with AIs results in out of sync error

[Jia Henry]

Hi

In Alpha 16, if a person drops out of a multiplayer game because of an error or some reason, and the person then rejoins the game, this produces an out of sync hash error.

This bug IS REPRODUCIBLE

It can be reproduced by:

Join a game, start playing, leave the game with or without resigning. Then rejoin the game. this will produce a out of sync hash error for ALL THE PLAYERS

However, this bug seems to have less of an effect if the game is paused whilst the person has dropped out and then unpaused, once they have fully joined.

Personally, I think this is because of the fact that the game does not take into account the time taken to sync the game play and download all of the data so when it syncs, the player who has rejoined is slightly "behind" al the other players.

The resolution of this bug is particularly urgent as it results in massive problems. For example, 1 player, kills another's civic centre but the other player doesn't know it and everything is still the same for the other player as they are out of sync.

This needs to be resolved ASAP.

[historic_bruno]

Are there any AIs in the game? Rejoining with AIs will cause an OOS.

Or it could be #2525 which wasn't fixed until after A16. The only way to know is to attach oos_dump.txt files for each player (see GameDataPaths).

[Jia Henry]

I have attached the oos_dump file

I have also noticed that at the time when I was having this error, my clock was 1 hour ahead of the correct time, which may also be a reason for this error

[Jia Henry]

I set my clocks right and this error still occurs.

It doesn't occur all the time but it only occurs when someone leaves and rejoins

[historic_bruno]

It's not related to time :)

The OOS dump says you were playing with AIs, that is a known problem and will break rejoining (due to #1089). Currently, you can't rejoin multiplayer games with AIs.

I will leave this ticket open, since I don't see one for this problem.

[Jia Henry]

That's strange, I have never played any multiplayer games with AIs since alpha 15.

[historic_bruno]

The OOS dump has players 3 and 4 listed as "aegis". Were those players assigned as AIs, humans or left unassigned? Can you verify the match settings?

[historic_bruno]

Also, if you can provide the OOS dump from all players, from the same game, we can compare the files and look for differences. Maybe something other than AIs are broken in rejoining, but we need more information.

[Jia Henry]

Hmm, I don't think I can provide the OOS dump from all the players because I don't remember who I played with and when I played.

I could however, setup a test environment in which I reproduce this bug and send you the OOS dumps for all the players.

Would that be helpful?

[historic_bruno]

Yes, thank you :)

[Jia Henry]

I did some experiments in some games and I found that this error does not occur if there's only a small amount of data to sync, for example in a 1v1 with a low pop cap.

However, in bigger games where there's a lot of data to sync, this error appears when someone tries to rejoin.

Here's a new OOS Dump file with details of only that one game in it.

The game is a 2v2 match with human players only.

[Jia Henry]

The new OOS dump file of 1 match where there are no AI

[sanderd17]

And can you get the oos dump of the other players too?

When researching an OOS, we need to find out what's different. So we need to compare both states.

[elexis]

This bugreport seems to be about the AEGIS AI which had been removed. There is #3858 with some linked commits that intends to fix Petra AI OOS on rejoin.