January 18
On Thu, Jan 18, 2024 at 04:23:16PM +0000, Renato via Digitalmars-d-learn wrote: [...]
> Ok, last time I'm running this for someone else :D
> ```
> Proc,Run,Memory(bytes),Time(ms)
> ===> ./rust
> ./rust,23920640,30
> ./rust,24018944,147
> ./rust,24068096,592
> ./rust,24150016,1187
> ./rust,7766016,4972
> ./rust,8011776,46101
> ===> src/d/dencoder
> src/d/dencoder,44154880,42
> src/d/dencoder,51347456,87
> src/d/dencoder,51380224,273
> src/d/dencoder,51462144,441
> src/d/dencoder,18644992,4414
> src/d/dencoder,18710528,43548
> ```

OK, this piqued my interest enough that I decided to install rust using rustup instead of my distro's package manager.  Here are the numbers I got for my machine:

===> ./rust
===> src/d/dencoder

Looks like we lost out to Rust for larger inputs. :-D  Probably due to environmental factors (and the fact that std.stdio is slow).  I re-ran it again and got this:

===> ./rust
===> src/d/dencoder

Notice the significant discrepancy between the two runs; this seems to show that the benchmark is only accurate up to about ±1.5 seconds.

Anyway, oddly enough, Java seems to beat Rust on larger inputs.  Maybe my Java compiler has a better JIT implementation? :-P

> Congratulations on beating Rust :D but remember: you're using a much more efficient algorithm! I must conclude that the Rust translation of the Trie algorithm would be much faster still, unfortunately (you may have noticed that I am on D's side here!).

At this point, it's not really about the difference between languages anymore; it's about the programmer's skill at optimizing his code.

Traditionally Java is thought to be the slowest, because it runs in a VM and generally tends to use more heap allocations.  In recent times, however, JIT and advanced GC implementations have significantly levelled that out, so you're probably not going to see the difference unless you hand-tweak your code down to the bare metal.

Surprisingly, at least on my machine, Lisp actually performed the worst. I'd have thought it would at least beat Java, but I was quite wrong. :-D Perhaps the Lisp implementation I'm using is suboptimal, I don't know. Or perhaps modern JVMs have really overtaken Lisp.

Now I'm really curious how a Rust version of the trie algorithm would perform.  Unfortunately I don't know Rust so I wouldn't be able to write it myself. (Hint, hint, nudge, nudge ;-)).

As far as the performance of my D version is concerned, I still haven't squeezed out all the performance I could yet.  Going into this, my intention was to take the lazy way of optimizing only what the profiler points out to me, with the slight ulterior motive of proving that a relatively small amount of targeted optimizations can go a long way at making the GC a non-problem in your typical D code. ;-)  I haven't pulled out all the optimization guns at my disposal yet.

If I were to go the next step, I'd split up the impl() function so that I get a better profile of where it's spending most of its time, and then optimize that.  My current suspicion is that the traversal of the trie could be improved by caching intermediate results to eliminate a good proportion of recursive calls in impl().

Also, the `print` mode of operation is quite slow, probably because writefln() allocates. (It allocates less than if I had used .format like I did before, but it nevertheless still allocates.) To alleviate this cost, I'd allocate an output buffer and write to that, flushing only once it filled up.

Another thing I could do is to use std.parallelism.parallel to run searches on batches of phone numbers in parallel. This is kinda cheating, though, since it's the same algorithm with the same cost, we're just putting more CPU cores to work. :-P  But in D this is quite easy to do, often as easy as simply adding .parallel to your outer foreach loop. In this particular case it will need some additional refactoring due to the fact that the input is being read line by line. But it's relatively easy to load the input into a buffer by chunks instead, and just run the searches on all the numbers found in the buffer in parallel.

On Thu, Jan 18, 2024 at 04:25:45PM +0000, Renato via Digitalmars-d-learn wrote: [...]
> BTW here's you main function so it can run on the benchmark:

Thanks, I've adapted my code accordingly and pushed to my github repo.


This is a tpyo.