Java > Scala

[Andrei Alexandrescu]

On 12/20/11 1:29 AM, Russel Winder wrote:
> The system as set out is biased though, systematically so.  This is not
> a problem per se since all the micro-benchmarks are about
> computationally intensive activity.  Native code versions are therefore
> always going to appear better.  But then this is fine the Shootout is
> about computationally intensive comparison.

This is fine, so no bias so far. It's a speed benchmark, so it's 
supposed to measure speed. It says as much. If native code comes usually 
in top places, the word is "expected", not "biased".

> Actually I am surprised
> that Java does so well in this comparison due to its start-up time
> issues.

I suppose this is because the run time of the tests is long enough to 
bury VM startup time. Alternatively, the benchmark may only measure the 
effective execution time.

> Part of the "problem" I alluded to was people using the numbers without
> thinking.  No amount of words on pages affect these people, they take
> the numbers as is and make decisions based solely on them.

Well, how is that a bias of the benchmark?

> C, C++ and
> Fortran win on most of them and so are the only choice of language.

The benchmark measures speed. If one is looking for speed wouldn't the 
choice of language be in keeping with these results? I'd be much more 
suspicious of the quality and/or good will of the benchmark if other 
languages would frequently come to the top.

> As I understand it, Isaac ruins this basically single handed, relying of
> folk providing versions of the code.  This means there is a highly
> restricted resource issue in managing the Shootout.  Hence a definite
> set of problems and a restricted set of languages to make management
> feasible.  This leads to interesting situation such as D is not part of
> the set but Clean and Mozart/Oz are.  But then Isaac is the final
> arbiter here, as it is his project, and what he says goes.

If I recall things correctly, Isaac dropped the D code because it was 
32-bit only, which was too much trouble for his setup. Now we have good 
64 bit generation, so it may be a good time to redo D implementations of 
the benchmarks and submit it again to Isaac for inclusion in the shootout.

Quite frankly, however, your remark (which I must agree, for all respect 
I hold for you, is baseless) is a PR faux pas - and unfortunately not 
the only one of our community. I'd find it difficult to go now and say, 
"by the way, Isaac, we're that community that insulted you on a couple 
of occasions. Now that we got to talk again, how about putting D back in 
the shootout?"

> I looked at the Java code and the Groovy code a couple of years back (I
> haven't re-checked the Java code recently), and it was more or less a
> transliteration of the C code.

That is contributed code. In order to demonstrate bias you'd need to 
show that faster code was submitted and refused.

> This meant that the programming
> languages were not being shown off at their best.  I started a project
> with the Groovy community to provide reasonable version of Groovy codes
> and was getting some take up.  Groovy was always going to be with Python
> and Ruby and nowhere near C, C++, and Fortran, or Java, but the results
> being displayed at the time were orders of magnitude slower than Groovy
> could be, as shown by the Java results.  The most obvious problem was
> that the original Groovy code was written so as to avoid any parallelism
> at all.

Who wrote the code? Is the owner of the shootout site responsible for 
those poor results?

> Of course Groovy (like Python) would never be used directly for this
> sort of computation, a mixed Groovy/Java or Python/C (or Python/C++,
> Python/Fortran) would be -- the "tight loop" being coded in the static
> language, the rest in the dynamic language.   Isaac said though that
> this was not permitted, that only pure single language versions were
> allowed.  Entirely reasonable in one sense, unfair in another: fair
> because it is about language performance in the abstract, unfair because
> it is comparing languages out of real world use context.

I'd find it a stretch to label that as unfair, for multiple reasons. The 
shootout measures speed of programming languages, not speed of systems 
languages wrapped in shells of other languages. The simpler reason is 
that it's the decision of the site owner to choose the rules. I happen 
to find them reasonable, but I get your point too (particularly if the 
optimized routines are part of the language's standard library).

> (It is worth noting that the Python is represented by CPython, and I
> suspect PyPy would be a lot faster for these micro-benchmarks.  But only
> when PyPy is Python 3 compliant since Python 3 and not Python 2 is the
> representative in the Shootout.  A comparison here is between using
> Erlang and Erlang HiPE.)
>
> In the event, Isaac took Groovy out of the Shootout, so the Groovy
> rewrite effort was disbanded.  I know Isaac says run your own site, but
> that rather misses the point, and leads directly to the sort of hassles
> Walter had when providing a benchmark site.

That actually hits the point so hard, the point is blown into so little 
pieces, you'd think it wasn't there in the first place. It's a website. 
If it doesn't do what you want, at the worst case that would be "a 
bummer". But it's not "unfair" as the whole notion of fairness is 
inappropriate here. Asking for anything including fairness _does_ miss 
the point.

> There is no point in a
> language development team running a benchmark.  The issues are
> perceived, if not real, bias in the numbers.  Benchmarks have to be run
> by an independent even if the contributions are from language
> development teams.
>
>> But I'm sure Russel had something in mind. Russel, would you want to
>> expand a bit?
>
> Hopefully the above does what you ask.
>
> The summary is that Isaac is running this in good faith, but there are
> systematic biases in the whole thing, which is entirely fine as long as
> you appreciate that.

Well, to me your elaboration seems like one of those delicious 
monologues Ricky Gervais gets into in the show "Extras". He makes some 
remark, figures it's a faux pas, and then tries to mend it but instead 
it all gets worse and worse.


Andrei