Scala等与C / C ++ / Fortran之间的性能比较？

Question

I wonder if there is any reliable comparison of performance between "modern" multithreading-specialized languages like eg scala and "classic" "lower-level" languages like C, C++, Fortran using parallel libs like MPI, Posix or even Open-MP.

Any links and suggestions welcome.

Answer 1

Given that Java, and, therefore, Scala, can call external libraries, and given that those highly specialized external libraries will do most of the work, then the performance is the same as long as the same libraries are used.

Other than that, any such comparison is essentially meaningless. Scala code runs on a virtual machine which has run-time optimization. That optimization can push long-running programs towards greater performance than programs compiled with those other languages -- or not. It depends on the specific program written in each language.

Answer 2

Here's another non-answer: go to your local supercomputer centre and ask what fraction of the CPU load is used by each language you are interested in. This will only give you a proxy answer to your question, it will tell you what the people who are concerned with high performance on such machines use when tackling the kind of problem that they tackle. But it's as instructive as any other answer you are likely to get for such a broad question.

PS The answer will be that Fortran, C and C++ consume well in excess of 95% of the CPU cycles.

Answer 3

I'd view such comparisons as a fraction. The numerator is a constant (around 0.00001, I believe). The denominator is the number of threads multiplied by the number of logical processors.

IOW, for a single thread, the comparison has about a one chance in a million of meaning something. For a quad core processor running an application with (say) 16 threads, you're down to one chance in 64 million of a meaningful result.

In short, there are undoubtedly quite a few people working on it, but the chances of even a single result from any of them providing a result that's useful and meaningful is still extremely low. Worse, even if one of them really did mean something, it would be almost impossible to find, and even more difficult to verify to the point that you actually knew it meant something.