Weird rumble scores

I've noticed that BeepBoop has been dropping in APS in the rumble lately. 0.14 should be a bit stronger than 0.13 and gets around 91.5 APS when I run a season against all rumble participants myself, but in the rumble it's at 91.2 APS and is quite a bit worse than 0.13. Does anyone have ideas about what could be causing the difference? The drop seems consistent rather than against a few problem bots, so the only thing I can think of is that it's skipping turns on some rumble clients but not when I run it myself.

I’m experiencing similar thing. Score is constantly dropping as more battles come.

But is’s not hard to explain.

1. For bots you get 100%, when getting more battles, it’s either changing to 100% or less than 100%, and the more battles the higher probability it gets less than 100%, so score can only decrease as more battles come.

2. For bots saving data, it’s only getting better the more data they have.

Since this affected a lot of bots, affecting 0.1~0.2 APS is quite common.

Worth mention that 1 APS decrease in 10 bots is enough to give you -0.1 APS.

Btw, 1 season is generally not enough to get stable results. For reliable result, 50000 or even 100000 battles are needed. Anyway comparing after ~30000 battles is generally acceptable.

I have noticed some weird outlier scores myself, and I don't think it's just those factors Xor.

The two battles of ags.Glacier 0.3.0 versus lxx.Emerald 0.6.5 that ran had an average APS of 26.04 for Glacier, yet when I ran those two bots manually on the same computer I had a rumble client on, I couldn't reproduce anything remotely that close to a score that low for Glacier, it was consistently >60 no matter how many times I ran it, usually >70. That's a massive discrepancy really, even with so few data points.

At the time the only rumble client besides my own on the same computer I couldn't reproduce an issue on, was "Xor_Sily". There's a chance it was just getting massively unlucky, but I'm rather curious what the result of manually running some ags.Glacier 0.3.0 versus lxx.Emerald 0.6.5 battles on the Xor_Sily computer would be.

If you are recording data, I can send you the files.

Anyway I’ve been long suffering outliner results, back to the days when optimizing SimpleBot. Score drop is huge after more battles sometimes (and Beaming is running rumble as well that days), and is yes not reproducible.

And that’s why Scalar series is called “scalar”. Because I’ve been optimizing performance exclusively since then, mainly leveraging Scalar Replacement to reduce GC overhead. And nowadays I’m suffering from outliner scores much less.

So yes, sometimes there is some outliner score. And the fact is either about some bugs, or GC overhead being too much (resulting a lot of skipped turns)

I'm not recording any data at this time no.

GC overhead is one potential issue, but I would argue that if rumble clients are causing massive skipped turns due to GC overhead, then the rumble client is likely badly configured, with something like too many rumble clients running concurrently for the number of CPU cores.

Java runs GC taking advantage of an additional thread generally, and it's normal for GC overhead to be significant for many bots, to the degree where I would argue that a rumble client should always be allocated two unused CPU cores, one for the main thread and one for GC thread overhead.

Since rumble clients are uploading scores after a few battles, it’s really hard that every core is used already. Not to mention that modern CPUs are great at reordering instructions, making room for more threads. So that leaving 1 more core for idle is completely wasting time & money IMO.

Anyway if rumble clients are commonly experiencing GC overhead, it could be solved by forcing full GC to run before each round. And if you’re still producing too much garbage even between rounds, it’s totally fine to be punished by skipped turns.

Anyway, GC overhead is always fair. If you are dealing with GC and skipped turns worse than the opponents, you get worse score, it’s perfectly judged.

I'm curious why you think GC overhead is always fair. Since GC overhead happens outside of the main thread, it can punish all robots in the same battle with a high degree of randomness. Not only that, if you're running a bunch of rumble clients on a computer, and the overall CPU usage on the system for all cores reaches 100% due to a couple clients having more GC overhead, then it could affect all bots in all active battles on that system, even in the other rumble clients.

Being fair means no one is getting advantage over it. And the ability to withstand ocationally skipped turns is part of the competition.

Since no one can guarantee that robots are always running with sufficent resource, I’m always on the side that robot authors should assume low performance computers.

"no one is getting advantage over it" is certainly untrue. Consider the notion of a bot that uses very little CPU in the main thread but creates lots of GC overhead, in a battle versus a bot that uses most of the typical CPU allotment but doesn't create much GC overhead. If this is on a system where the GC thread can affect the time available to the main thread (i.e. don't have enough spare CPU for the GC thread), then the bot that uses very little CPU in the main thread but is creating lots of GC overhead will be advantaged by causing the GC overhead, since it would cause more skipped turns for the other bot but not so much itself. This is somewhat of an extreme example, but the point is that skipped turns caused by GC overhead are anything but fairly distributed.

You are right. Apart from creating many thrads that do a lot of work when it’s others turn, creating a lot of objects to increase GC overhead does affect others’ bots as well, making the result a little bit random.

But I doubt how much difference can GC overhead put. The most unreproducible scores I experienced are always coming from some rare exceptions, say 1/1000. And once happened, it causes some random pairing to be close to 0. If averaged with some normal score, it really looked like it’s decreasing with no reason.

So my advice is that you output exceptions to file, and check if there are any. Skipped turns could also be counted. I was doing this in older bots as well, and concluded that GC overhead & skipped turns aren’t really rhe problem, but exceptions are.

But there’s always some reason, and mostly coming from specific bot instead of the clients, since not everyone is affected.