Client java version

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Edited by author.
Last edit: 21:54, 5 September 2017

Perhaps we should all give more details about how we run the rumble client.

I run RoboRumble intermittently, not continuously (only when I see interesting new bots added to the participants list). So far, I've only run roborumble (not meleerumble or others), but that may change soon. (Edit: As of September 5, 2017 8:49 PM CET, I have started running meleerumble). It's running on my everyday-use computer, and not a dedicated machine. Sometimes I run Robocode battles or browse to CPU-intensive webpages, and that may cut into the amount of CPU the client gets. My CPU constant is 6500859 ns (6.5 ms) per turn. I have a 4-core machine, and RoboRumble tends to take up 30-60% CPU constantly. It takes about 15 minutes to execute 50 battles.

Seriously though, if your robot is incompatible with certain setups, the fault lies in your robot. Perhaps you should respond to SkippedTurnEvents by reducing the amount of computation your robot performs.

MultiplyByZer0 (talk)17:33, 4 September 2017

Running the rumble client on an ultrabook when I'm not using it and it is plugged into power. Often it uses 2 cores even with a single client. CPU constant is about 5.3ms in openjdk8 using Linux.

About the skipped turn thing, I agree. A big part of Robocode is how long you have to do your processing in. It is a massive tradeoff and I know some of my bots occasionally step over the edge. However, I also don't want to change the rules of the competition. If there is something in Oracle JDK8 that is killing certain bots we need to figure out what that is.

Skilgannon (talk)19:43, 4 September 2017

I am not arguing that heavy on skipping bots should not be punished, my complain that it is erratic and seemingly coming from Java itself. Looks like it shows when a heavy bot is matched against a low CPU demanding one.

By the way, sometimes it to my advantage. I see strange unexplainable APS gain in melee against 'sgp.JollyNinja 3.53' [1]

Note that my v7.4 is very mediocre when compared against v6.1, except one case JollyNinja.

Beaming (talk)20:09, 4 September 2017

Heavy vs light causing problems sounds to me like a race condition. And I think this might even be a separate issue from MoxieBot getting 0. This clearly needs further investigation.

Skilgannon (talk)20:39, 4 September 2017

I took a look at your results. Your bot is performing below expectations, most prominently with 37.71% survival against sample.Crazy (???), which I cannot reproduce on my own computer.

I do agree that bugs (particularly ones that produce unfair results) ought to be squashed ASAP. However, you cannot expect the amount of work-per-turn your bot is allowed to perform to remain constant between machines (and possibly not even between battles or rounds). Perhaps a CPU-intensive background process is running, or the user decides to play video games, or the OS starts throttling Java, or the CPU drops to 0.15 GHz for no good reason (I've actually seen that happen), or gamma rays hit your computer and flip a bit in the tick time counter, or whatever.

My point was that high-CPU bots must adapt to changing circumstances. Too many bots just ignore SkippedTurnEvent, when it's practically a blaring flashing-red-lights warning from Robocode. You could respond by reducing CPU load, e.g. disabling features, virtual guns, second wave surfing, etc. It's better for your bot to function suboptimally than to not function at all.

MultiplyByZer0 (talk)21:18, 4 September 2017

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Return to Thread:Talk:RoboRumble/Client java version/reply (29).

While I take the blame for my bot performance.

I would claim that I am not ignoring the skip turn event. I have a counter for it, and I release bots which keep it low through the game. Typically in the rumble, it reports zero about every second round in 35 rounds game, in 45% rounds it is 1; in 2 or 3 rounds it spikes up to 7 or even 15 per round. Even 15 skips per 700 turns games is not too much to loose a game to sample.crazy with HoT gun.

So I still think it is the "Thread.Death" which is probably triggered by skipped turns.

I will try to reduce the bot CPU demand and see if the problem goes away.

Beaming (talk)02:42, 5 September 2017

ThreadDeath is just Thread.stop() doing its job.

See this article.

MultiplyByZer0 (talk)01:48, 6 September 2017

Are we actually talking about time-per-turn problem? I supposed, given the age of Robocode and Roborumble, that this is a well discussed topic and that every possible decision to make the system work fair enough while providing the "contributing" feature was already made. It seems that what we are talking about here is a bug. I know every environment is not equal, but even with the very little time I have on Robocode I could conclude a robot should work under the assumption that at least a reasonable quota of its turn time will be respected (even if in reality it's not eventually). If that quota is not being respected even after like, 10 battles, in a machine that is OK, and the results are absurd like the results Beaming reported, there must be a bug somewhere, even if it's on Beaming's side, and IMO it's worth it to discuss it and, maybe, to find it, since it may explain some other weird behavior in the future.

Rsalesc (talk)02:13, 5 September 2017

Here is my setup,

I run literumble clients on two machines almost non stop. Each runs one rumble and one melee client at the same time. Since one has 4 cores and the other 6, this should not be a problem with CPU calculations under normal circumstances. Also, there is plenty of RAM so no swapping. If I expect high CPU demanding tasks, I stop clients so they not affected by CPU fight with other programs.

All my machines are 64 bit linux with openjdk-8-jdk-headless.

But I think at some point robocode became multi-threaded, so CPU constant (6.5 ms in my case) is not so relevant anymore. In top, I can see that rumble client often eats more than 100%, i.e. it spans between cores. Also, load on a machine seems to be high, i.e. it is often in the range of 3 for the 6 cores machine.

Plus there is CPU throttling which kicks in when ever it wants, thanks to modern hardware design.

Beaming (talk)20:16, 4 September 2017

I don't think Robocode actually runs more than 1 thread at a time. I think the extra CPU is from the JVM JIT optimizer running in parallel.

Skilgannon (talk)20:41, 4 September 2017

I meant the whole robocode machinery. I recall that couple years ago the robocode client (and its java) was confined to one CPU, today it is not the case. See the attached screenshot.

htop screenshot

Beaming (talk)03:14, 5 September 2017