Loss of sync after queuing up large square of units

[bluesun]

Queuing up a large square (shift-alt) of units causes a loss of sync in multiplayer. When sync is lost, units no longer respond to commands. Airplanes start slowly moving upward (Z+, no change in X or Y). On the side (computer) where the units were queued, no status or chat messages are shown, but chat messages and things like a pause command, sent from the computer where the units were queued, still show up on the other players' screens. This bug effects AA v0.32 and XTA v0.65 SE with TA Spring 0.65b2. It may (most likely does) effect other mods as well.

Steps to reproduce:

1. Start a multiplayer game with either of the above-mentioned mods.
2. Build an aircraft plant and a few construction planes. (This is optional, but will illustrate the plane-rising part of the bug.)
3. With your Commander, click to build a wind power generator (any unit should work). Hold down Shift and Alt, then queue up a large square - at least 20x20.
4. Watch as your Commander doesn't do anything. Within a few seconds, all construction and movement will stop. Your airplanes will begin rising, and will eventually wrap around to the bottom of the map.

If you need any more information, or if there is somewhere else that bugs like this should be posted, please post a reply. Thanks.


UPDATE: Just consolidating some clarifications from below:

• Both players were on broadband connections with adequate hardware. (3.2GHz P4 + 1GB RAM, AMD 2600+ + 512MB RAM)
• We waited for several minutes to regain sync. Eventually we gave up - if it can't be done after that long with both players on broadband, it's not going to happen.
• This happens regardless of the number of queued buildings that can actually be built. If you do it on flat terrain and all of them are buildable, or if you do it on rugged terrain and only a handful are buildable, it doesn't matter.
• The thing with the airplanes rising is apparently an intentional feature of the game. However, there's still the problem of the unrecoverable loss of sync.

[Min3mat]

i get lag when doing this with 30 odd con planes when i have a few other queued up buildings. my advice is upgrade your PC (or if u r cheap simply host ur own games and disable air cons

[jcnossen]

I've tried it as a server(singleplayer) and only a small part of the box of units was actually ordered. So I guess there is a problem with some sort of limit involved. Maybe I'll try to see what's actually happening sometime... and fix it.

[Maelstrom]

Ive noticed the capping of the orders as well. Witht he capping, it means it takes quite a while to build a huge square of Energy Storages. heh, those make some nice explosions when they set up a huge chain reaction .

[bluesun]

Min3mat wrote:

i get lag when doing this with 30 odd con planes when i have a few other queued up buildings. my advice is upgrade your PC (or if u r cheap simply host ur own games and disable air cons

It's definitely not my computer. I have a P4 3.2GHz with hyperthreading and 1GB of RAM, and my internet connection is 10Mbit down/1MBit up. I regularly build swarms of hundreds of planes with minimal slowdown. Besides, the game freezes (stops accepting input, or at least stops responding to it) and never recovers; if the problem were that my computer is too slow, then the game would just slow down. (Also, presumably the weird thing with the planes rising wouldn't happen.)

Zaphod wrote:

I've tried it as a server(singleplayer) and only a small part of the box of units was actually ordered. So I guess there is a problem with some sort of limit involved. Maybe I'll try to see what's actually happening sometime... and fix it.

I've seen it both ways, in terms of only some units being actually ordered. I first saw this bug when I square-queued a large area with rugged terrain. I wanted to build Flakkers wherever possible in a mountainous region, so I just square-queued a huge area, even though only a few Flakkers were on level enough terrain to be built. Even though only 10 or so of the 400 or so "queued" Flakkers were buildable, the game still lost sync and stopped responding, and the planes still did their slow rising thing.

The second time, I was queuing up a huge square of wind generators on a flat area, so it was indeed possible to build them all. Unfortunately, I hit the bug again, and the game was over (since I couldn't do anything, and my opponent was told that I was out of sync).

Maelstrom wrote:

Ive noticed the capping of the orders as well. Witht he capping, it means it takes quite a while to build a huge square of Energy Storages. heh, those make some nice explosions when they set up a huge chain reaction .

This could be a game-enforced cap on queue size, but if it is, it's very strangely enforced. Effectively ending the game by freezing out one of the players is not exactly a helpful way to indicate an intentional game limitation...

Thanks for everyone's input. If other people see this behavior, or if I get more information, we should keep posting here. Hopefully one of the devs will get a chance to look at it at some point, and maybe track down the bug (or tell us about the "feature" )...

[Maelstrom]

Well, what happened to me was that I built a huge square, and only a portion of them were built. I didnt loose sync. (actualy, I was playing single player, so I dont know if I would loose sync anyway).

Perhaps it was the other persons computer/internet connection that couldnt handle the load?

[LocalFiend]

*mutters, bloody air con swarms, grr.... anyway, I'm not sure about why you're losing sync, but the floating aircraft is normal for when you do lose sync. When the connection is totally brokend and or blocked for a few seconds, all units continue to move in the direction they were going, albiet, without animation. It makes for smoother transistions when your connection is re-established. Meaning, your comp doesnt have as much catching up to do.

[bluesun]

Maelstrom wrote:

Well, what happened to me was that I built a huge square, and only a portion of them were built. I didnt loose sync. (actualy, I was playing single player, so I dont know if I would loose sync anyway).

When I get a chance, I'll try it in single player - that'll give us more information, at least...

Perhaps it was the other persons computer/internet connection that couldnt handle the load?

It's a possibility, but it seems unlikely. He's on a broadband connection as well, with a respectable machine (AMD 2600+, 512MB RAM).

LocalFiend wrote:

*mutters, bloody air con swarms, grr....

Teehee :)

anyway, I'm not sure about why you're losing sync, but the floating aircraft is normal for when you do lose sync. When the connection is totally brokend and or blocked for a few seconds, all units continue to move in the direction they were going, albiet, without animation. It makes for smoother transistions when your connection is re-established. Meaning, your comp doesnt have as much catching up to do.

That's good to know. It certainly looked to me like they were rising straight up, though, as opposed to continuing to move in the same direction as before. Could that make a difference?

Either way, we waited for at least a minute before giving up on regaining sync. I'd find it very hard to believe that two players with broadband connections couldn't resync after a full minute, so it still seems to me that this is most likely a bug...

[SinbadEV]

simmilar issue... tried to build like 100 DTs, then none of my units could be issued new orders, but acctually could see what was going on, it was like the server had stopped listening to me

[Maelstrom]

IIRC, sync does not have much to do with connection speeds. It has to do with if the Spring engines on the two different computers are running at the same point. Sync errors can be CAUSED by bad connection, but once the error is there, connection has little or nothing to do with regaining sync.

Now, what I say is probably wrong, so dont listen to me too much.

[jcnossen]

Either way, we waited for at least a minute before giving up on regaining sync. I'd find it very hard to believe that two players with broadband connections couldn't resync after a full minute, so it still seems to me that this is most likely a bug...

Resync is *not* possible. Maelstrom is right, however in theory sync errors can't caused by a slow connection (I've never actually seen it happen, but if it does it would be a networking bug...)
What the engine does is generate a checksum based on all the unit positions and the player energy/metal. These checksums are sent every frame, and if the server notices that one of the players send a different checksum, it starts complaining about sync errors.
Now you can also see why an active cheat is hard to make here.

[NOiZE]

the host can cheat easily thou :D

[AF]

Once I got a sync error like those on my computer playing a version of NTAI (not the version on fileunvierse), and it started unsyncing, and it lagged like hell, made worse by the fact that the AI was then logging the sync messages to the AI log hmtl file. I wasnt online either, just running spring directly and choosing GlobalAI script.

Suffice to say firefox couldnt handle the AI log files which soemtimes ran in excess of 1.4GB

[bluesun]

SinbadEV wrote:

simmilar issue... tried to build like 100 DTs, then none of my units could be issued new orders, but acctually could see what was going on, it was like the server had stopped listening to me

This is very similar to what happens to me, except that while I could "see what was going on" with my units, there wasn't anything actually going on - nothing was moving except for the airplanes, and they were only going upwards. I couldn't see anything my opponent was doing, though, but that's normal with fog of war.

Zaphod wrote:

Resync is *not* possible. Maelstrom is right, however in theory sync errors can't caused by a slow connection (I've never actually seen it happen, but if it does it would be a networking bug...)
What the engine does is generate a checksum based on all the unit positions and the player energy/metal. These checksums are sent every frame, and if the server notices that one of the players send a different checksum, it starts complaining about sync errors.
Now you can also see why an active cheat is hard to make here.

Ah! That's good to know. This makes it sound even more like this is a bug, then - the queuing up of all those units probably caused some glitch in the sync system.

Alantai Firestar wrote:

Once I got a sync error like those on my computer playing a version of NTAI (not the version on fileunvierse), and it started unsyncing, and it lagged like hell, made worse by the fact that the AI was then logging the sync messages to the AI log hmtl file. I wasnt online either, just running spring directly and choosing GlobalAI script.

I haven't yet tried this in single-player, but I will shortly. I'll post an update here with the results.

[AF]

aha corrrection, it doesnt say loss of sync, it says overflow, then something about delayed request for wrong frame. It's a horrible thing that plagues me regardless of which AI I use or if I use it at all.