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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.
2 would explain a bit of a score decrease, although not that many bots save data. I don't think 1 is true; sure some 100%s will become 99.5%s but also some 99%s will move up to 99.5%. Without 2, the APS estimated from a small number of battles should be an unbiased estimate of the true APS. And it takes 1 APS decrease in 100 bots to get -0.1 APS since there are ~1000 bots in the rumble!
Have a look at 0.14 and 0.14a, the APS is 0.3 diff. And if only looking at the simplest bots to beat, 0.14a is having more 100% than 0.14, simply because it haven’t got enough battles.
99% going to 99.5% does happen, but they do move to 98.5% as well. It’s mostly balanced.
But the 100% part is onesided, causing it to constantly move down before reaching some “stable point”.
0-1 is balanced, but since you don’t get 0, it’s unbalanced then. Averaging on unbalanced distribution is biased sometimes, there exists better calc of APS to avoid score shifting, e.g. Using walson score lower bound for each bot instead of some 40 window moving average.
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.
I think you are right. Clients should be allocated with one extra core for GC to be ran on background. Forcing full GC each round could also be added to rumble client.
And I think the extra core should be enforced by rumble clients
Anyway the optimal cpu ratio needs some experiments, but battles seems to run even faster when some cores are dedicated for GC.
And I’m not sure whether rumble clients shall be restarted after many battles. If there were some memory leaks in robocode, performance will drop overtime, resulting APS drop in newer bots.
It's not per-round so much as per-battle, but I will note that Robocode does make some System.gc calls at end of battle.
It's also the case for a very long time I've been in a habit of including System.gc() in the constructor of my bots, so that'd end up being per round.
That can only be Xor_Sily, that is the only one that has run battles in after you uploaded version 0.15
Did you manually set the CPU constant in your robocode install ? Maybe Xor has to recalculate the CPU constant for Xor_Sily, if the machine it is running on has become heavier loaded.
The cpu constants of Xor_Sily is computed when all cores are used, and currently I’m using only half of the cores as suggested by Rednaxela. So maybe the cpu constant is a little bit loose, making skipped turns happen LESS. If a bot isn’t skipping turns in ordinary configuration, it shouldn’t skip turns on Xor_Sily.
If anyone is logging data, I could help by sending the files.
Isn't using half of the cores also half the performance, so taking twice the time, so ideally twice the cpu constant ?
I know the difference now, Xor_Sily has no turbo boost support, so cpu constant is accurate. On most computers, cpu constant is actually much loose, because actual battles are run with turbo boost, but cpu constant, not. This is making skipped turns happening LESS.
I'm not sure I follow: what you are saying suggests that skipped turns should happen more on Xor_Sily right? I assume the reason for BeepBoop's low scores is it skipping lots of turns.
As an aside, I've also noticed that DrussGT 3.1.7 has also dropped 0.3 APS compared to 3.1.6, maybe it is also getting bad battles with lots of skipped turns?
I mean if you run battles on computers without turbo boost, you should get identical results as Xor_Sily.
Looks like the weird battles are produced on Xor_Sily. I will run some battles using these bots manually on Xor_Sily, to see what's happening.
Btw I'm not experiencing weird results personally, battles ran in local have similar results in rumble. How many cores are u using when running local battles?
Thanks for looking into it! I'm using 4 cores when running local battles.
Another info, are you using turbo boost enabled computer? I suspect this makes cpu constants inconsistent. Since cpu constant mostly happens when load isn’t high and turbo isn’t enabled.
Stopping Xor_Sily seems to have fixed things, with BeepBoop's scores finally matching what happens when I run a season myself! I also did some profiling to make sure BeepBoop isn't a SlowBot. On average it takes <80% of the time per tick of DrussGT and <50% of Diamond. For the 99.9th percentile of slowest ticks it is slightly (<10%) slower than DrussGT and slightly faster than Diamond, so I don't think it should be skipping turns any more often than them.