Comment by igouy | Hacker News Reader

Comment by igouy | Hacker News Reader

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1) Of all the things the data can be used for, one of the least useful ones -- to the point of being nearly meaningless -- is comparing the performance of different languages to each other, the thing that the game's presentation emphasizes most.

Is that what the presentation emphasizes most?

"Will your toy benchmark program be faster if you write it in a different programming language? It depends how you write it!"

"Which programs are faster?"

"Which programs are fast?"

"Non-motivation: We are profoundly uninterested in claims that these measurements, of a few tiny programs, somehow define the relative performance of programming languages."

2) Or look even at "Java" vs "Substrate VM" pidigits.

Currently 2 Java pidigits programs are shown.

The program with the fastest measurements on OpenJDK uses GMP and something different needs to be done to make that program work on Substrate VM.

3) …but crashes, and what appears to be some junk result is reported.

What is reported? Measurements at the largest workload both programs worked.

4) examples … you… seem to say, see, warmup doesn't matter

See, for programs with runtimes of 0.24s, 1/10th of a second is a lot!

See, for programs with runtimes of 4s and 20s, 1/10ths of a second… !

5) Now I'm looking at Haskell's fannkuch-redux

And… ?

6) … if the comparison was for the same language (and compiler) then this would be interesting, but what does this tell you when comparing different languages?

That seems to be a subjective statement about your interests.

Someone else might think that neither "tell you" much until you investigate Why?

> Is that what the presentation emphasizes most?

Yes, because that's what the site shows most prominently: comparisons between languages.

The fact that the explanations to the benchmarks basically say that these comparisons mean nothing doesn't make the comparisons mean much more than nothing, especially as there's no explanation to what the comparisons do (or are supposed to) mean. So in addition to having no hypothesis, no analysis and no exposition, there's a notice saying, don't use these comparisons for so and so. Then what are those comparisons for?

Again, I don't think the game's comparisons are worse than many other benchmark comparisons out there, but that doesn't make it good. What's unfortunate is that unlike those other benchmarks, they have a lot of data that could be used for some really cool stuff (not to compare languages).

It's possible that the language competition is meant to encourage more people to submit and show how their favorite language wins, but there's no information about the market aspects.

> See, for programs with runtimes of 4s and 20s, 1/10ths of a second… !

I run a toy benchmark that's the same size as the game's, and HotSpot's C2 gives me a 30-50% boost after ~10s. It really varies by program (not by problem). This tends to be worse for programs that use a lot of parallelism and aren't configured to run compilation in blocking mode, because then the application threads compete with the compilation threads, but again, there isn't really a good rule of thumb here. In any event, it is simply wrong that C2 would never yield significant performance boosts after a few tenths of a second, even on small programs (it may be true for some specific benchmark entries and maybe even all current ones, it may vary by JDK version, and it definitely varies on whether HotSpot uses Graal or C2). Although, given all the other serious problems that render the comparisons mostly meaningless (different algorithms), my guess would be that this effect is smaller by comparison.

Still, there's a lot of cool stuff the game could do with the current programs (and historical ones), but comparing languages is not really one of them.

> … what the site shows most prominently…

Program after Program after Program.

https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

Of course, it's really not possible to show any computer program which is not written in a programming language.

> … basically say that these comparisons mean nothing …

Obviously not: please don't put your words in others' mouths.

> … a lot of data that could be used for some really cool stuff…

Take the data and do that really cool stuff.

https://salsa.debian.org/benchmarksgame-team/benchmarksgame

> … but there's no information about the market aspects.

What do you mean by "market aspects" ?

> …it may be true for some specific benchmark entries and maybe even all current ones…

So it would be wrong to try to dismiss those measurements, based on nothing more than extrapolation about how some other toy benchmark program might perform.

> … cool stuff the game could do …

You're allowed your own personal opinion about what's cool and what isn't (and no doubt others will have their own personal opinion).

> Obviously not

It's certainly not obvious to me what they comparisons mean (is it obvious to you?) and the authors of the site don't even state, let alone support, a hypothesis. They just say what the comparisons don't mean. So unless it's a work of art, I think observers can be forgiven for thinking it doesn't mean anything.

> What do you mean by "market aspects"?

I mean a hypothesis about "free market competition" driving people to write really fast programs.

> You're allowed your own personal opinion about what's cool and what isn't

True, but I meant something that could be used in a more rigorous/meaningful way (e.g. comparisons where only one variable changes). Meaning is perhaps also subjective, but I don't even know the subjective opinion of the meaning behind the game, because the site doesn't say.

> https://salsa.debian.org/benchmarksgame-team/benchmarksgame

Cool.

Anyway, now that I've taken a slightly closer look, I realize I spoke too soon when I said that the SBCL vs. Java benchmark is "better than nothing." If, say, Java uses parallelism while SBCL doesn't, then if Java is 4x faster that may not be a "better than nothing" indication.

> not obvious to me

Program X measured less than Program Y.

> … comparisons where only one variable changes…

Seems like your idea of a comparison, between for-example Lisp and Java programs, would require writing all the Lisp programs as if they were being written in Java. (We used up our "one variable change" with SBCL instead-of OpenJDK).

> I spoke too soon

You chose to summarize data: "Java outperforms SBCL by a very wide margin -- 1.25-4x faster".

Do you mean that you made mistakes when you made your summary.

> Program X measured less than Program Y.

That's like asking what does a program do and being told, "it does what the code says." Technically true, but not what we mean when we ask. Also, I don't think that's really what the site's authors thought. After all, when I click on the Haskell page, I don't see a comparison of Haskell programs, but a comparison of the fastest Haskell program with the fastest Java program. It's not obvious to me what that means, or even that it means anything at all.

> Seems like your idea of a comparison, between for-example Lisp and Java programs, would require writing all the Lisp programs as if they were being written in Java. (We used up our "one variable change" with SBCL instead-of OpenJDK).

That's exactly right, but because that's rather tedious, I would present just meaningful comparisons rather than non-meaningful ones, so no inter-language comparisons. I'm not saying they're always meaningless, but they can't be made with the data currently available on that site. Unfortunately, we cannot manufacture (non-fictitious) meaning out of data as we like.

> Do you mean that you made mistakes when you made your summary.

Yes. By "better than nothing" I overestimated the significance of results, at least in this case. After a closer look I realized that different programs use different algorithms, and so the comparison tells me nothing about the relative speed of those languages.

> That's like…

No it is not. Program X may not have measured less than Program Y.

> … meaningful comparisons…

Earlier you complained there was "code that's very unidiomatic" but now you say "writing all the Lisp programs as if they were being written in Java" would be exactly right?

1) You seem to be contradicting your own argument.

2) Your desire for "rigorous" comparison is in-conflict with your desire for inter-language comparison.

> … different programs use different algorithms…

For some programs, for some definition of "algorithm".

> … the comparison tells me nothing about the relative speed of those languages.

What is the speed of a programming language?

> Earlier you complained there was "code that's very unidiomatic" but now you say "writing all the Lisp programs as if they were being written in Java" would be exactly right?

I may have misinterpreted your comment. By "as if they were written in Java" I meant using a similar algorithm. Alternatively, there could be a rule about idiomatic code (enforced by experts), which would compare very different things, but would also be at least somewhat meaningful.

> For some programs

I don't know. Whenever someone refers me to a result on that site that looks weird, I see very different algorithms.

> for some definition of "algorithm".

For a very well-accepted definition of an algorithm in the context of real performance comparisons.

> What is the speed of a programming language?

I'm not sure (although perhaps I could come up with some definition given enough thought), but I didn't make a website that compares languages based on performance. In fact, I said that the website is totally meaningless. But the people behind it may have something in mind, and if they do, they're not telling us. All I can do is think of ways to use the site's data in ways that can at least be meaningful.

> … a similar algorithm.

Will someone else look at those similar algorithms and "see very different algorithms"?

> … a result on that site that looks weird, I see very different algorithms.

Do regex libraries for different languages in-fact always implement the same algorithms?

> What is the speed of a programming language? I'm not sure…

You did say "Java outperforms SBCL by a very wide margin -- 1.25-4x faster".

Saying "… so the comparison tells me nothing about the relative speed of those languages" suggests you are looking for something that tells us about "the relative speed" of those languages?

> Will someone else look at those similar algorithms and "see very different algorithms"?

I would think so.

> Do regex libraries for different languages in-fact always implement the same algorithms?

I don't know. But I do know that when something is presented as an answer, it's good to know what the question is.

> suggests you are looking for something that tells us about "the relative speed" of those languages?

I can think of a couple of ways the two can compare. One is the relative speeds (and other metrics) of programs of a similar nature, written simple idiomatic code. This gives a general "feel" for what kind of workloads different languages may be suitable for. Another is comparing the performance of the compiler/interpreter on some microbenchmark of the same algorithms, preferably written by people who coordinate, and preferably without mixing too many variables (e.g. measuring parallel scheduling separately and regex separately). Either one of these is of some interest.

The benchmark game does neither. If there is some idea behind the site's comparisons, it's certainly keeping it a mystery.

> … relative speeds (and other metrics) of programs…

So when you say "the relative speed of those languages" you actually mean the relative speed of programs?

> … programs of a similar nature … preferably without mixing too many variables…

Seems vague, no-longer rigorous.

We can make mystery for ourselves — no one can force us to understand.

> So when you say "the relative speed of those languages" you actually mean the relative speed of programs?

No, I mean the relative speed of programs with some carefully chosen relation between them. For example, there is a big difference between "relative income of individuals" and "relative income of social groups," even though the latter could be reduced to the former. Whether a comparison of individuals is meaningful as a comparison of groups depends on how the individuals are chosen and aggregated. Clearly not every choice of individuals would make for a meaningful comparison of groups and not every choice of programs makes for a meaningful comparison of languages. The choices made by the game do not seem at all meaningful for the comparison of languages, but if there is some rhyme or reason to the choice, the website doesn't say what it is.

> We can make mystery for ourselves — no one can force us to understand.

True, but when a website chooses to present data in some aggregate way that seems to defy any familiar forms of aggregation and reasoning without so much as stating what the meaning of the presentation is, it is itself mysterious. I agree that it is possible that the comparisons are not worthless, but without any statement of a hypothesis, it is the most reasonable conclusion. I am sure that the authors of the website would agree that if they don't even attempt to say what the meaning of the comparisons is, even in their own minds, it is reasonable to assume it means nothing.

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