THIS desyncs: syncdebug logs

[KingRaptor]

Technically this belongs in Games and Mods Discussion or Help & Bugs, but I'm posting this here because that's where you engine dev boffins hang out.

The grav flak weapon in THIS is causing desyncs. I've run several tests with the 0.8.4.2 syncdebug build, and I need someone who can make sense of the logs. Mod is here if you need to watch the included replays or look at the game code.

Help much appreciated

[imbaczek]

well done on your first try, but it wasn't a complete success: you didn't get the debug symbols (or spring can't read them.) this severely limits the usefulness of provided logs. getting debug symbols should be easy; it's on buildserv in the debug directory (instead of installer.)

one thing that you can try is playing in a window against yourself on only one computer - if the desync is in lua, you should be able to find it this way with the help of the sync debugger.

what's immediately interesting is this:

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Server: bad flop# 1955698 instead of 1955696 for player 1

basically, this means that player 1 didn't calculate something player 2 (or 0) did. this may be (usually is) a result of doing synced calculations based on unsynced conditions.

[hoijui]

doh!
totally forgot about that (that one needs the debug symbols separately). sorry KingRaptor (i was around when he asked for instructions about sync-debugging).
this is the Wiki page, in case you did not yet see it:
http://springrts.com/wiki/Debugging_sync_errors
you essentially did eveyrthing except 5. on that page.

[Kloot]

Reproduced it with two local clients (compiled with L2 debug symbols) by issuing

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/cheat
/give carrier 0
/give carrier 1

as in the 1_2carriers demo, so hopefully we'll know soon enough.

[Kloot]

Traced the carrier vs. carrier torpedo desyncs to dronelaunchers.local.lua; after commenting out

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table.insert(spawnList, {
	drone=drone, target = target, rotation = math.pi*.5*rotation, pitch = pitch or 0, team = team,
	x=x,y=y,z=z,dx=dx,dy=dy,dz=dz,
})

they disappear. But this isn't sync-unsafe code (unless insert interprets the second argument as a position), so the real cause should be somewhere inside GameFrame.

e: the drone GameFrame logic wasn't responsible after all, it just added to the snowball effect.

[imbaczek]

wonder if there's a way of dumping the whole lua state? we could checksum only synced lua state to provide feedback to mod developers that it's their fault. syncdebug could perhaps dump and transfer the whole state for easy diffing.

as an added bonus, the code could be reused for saving games.

[Tobi]

A complication would be that entire LuaRules (both synced and unsynced) runs in the same lua_State. So you'd actually have to track down which objects belong to the synced part, or which belong to the unsynced part.

(Or better, do the LuaRules synced/unsynced split trepan still wanted to do before he left.)

[KingRaptor]

It turns out I made a pretty flagrant bug in perks.locals.lua (declaring the local variable teams for the whole gadget when I only wanted it in Initialize() x_x), which cleared up a lot of problems when it was fixed. Sync error with 2 carriers (and likely other stuff) remains however.

EDIT: Drone controller (dronelauncherm) unit desynced when struck with grav-flak. Daggers did not desync when hit by same weapon. Drone controller did not desync under normal conditions even when drones were intercepted by Wraiths.

Suspect desync may be connected to drones being killed on same frame as spawn or similar issue. Attempt to replicate by spamming Wraiths to kill drones on spawn failed - unable to kill fast enough.

[Kloot]

Thanks, but those carrier vs. carrier and other desyncs should already be fixed upstream (there was a dormant engine bug that got triggered by the perk system). If you can, try the master build.

[KingRaptor]

All known desyncs not reproduced in 0.80.4-356-g27d791f committed 2009-10-15