The compiler will optimize that away • Hacker News Board

Re: The compiler will optimize that away

#61

Post by lordnacho » Sun, May 02, 2021, 11:14 AM UTC

tgaj wrote: post #44

lordnacho wrote: post #13

Good article. My own thinking when coding performance is also towards data oriented approaches. For example Bevy in Rust. If stuff needs to be fast, it needs to be in cache. To do that, have everything nicely packed so you only ask for a chunk as often as you need. Then when you need it, it's already there. Thing about old fashioned OO is it's often fine enough for your run-of-the-mill CRUD app. If you look at the la…

> If you imagine a game that has characters, relationships, items, spells, and so on, it's often not that easy to model as encapsulated objects. Does each character have a list of other characters that they have a relationship with? What happens when you want to change the relationship, or a character casts a spell that temporarily changes the relationship? Can easily end up a mess, because it's not obvious where suc…

But splitting it out into another class is halfway there already, no? The relations object doesn't correspond to a real domain object anymore. Next step is just to split out all the other components.

Re: The compiler will optimize that away

#62

Post by theamk » Sun, May 02, 2021, 11:41 AM UTC

tom_mellior wrote: post #40

theamk wrote: post #2

Summary: the computer has changed -- memory latency measured in CPU cycles has grown a lot. So we should not be using traditional struct/class-like programming model, where we put all properties of an object next to each other. Instead, we should be using game-style "data oriented programming" a.k.a. "column databases" for a much higher performance. However, most modern languages (C, C++, Python, Java, etc..) are not…

> However, most modern languages (C, C++, Python, Java, etc..) are not making it easy, The article shows how easy it is to declare a struct of arrays in Java: You declare a struct (class). Inside it you declare arrays. Done.

The code you to actually use it is pretty dangerous - you need to keep the index and “main pointer” in separate variables, but always use them together. And indexes are all plain untyped integers, so no compiler will warn you if you use wrong index variable. And GC is no longer thing, so “write after free” and friends come back.

Going to column arrays in high-level languages brings back many of the C bugs that we really hoped to forget.

Re: The compiler will optimize that away

#63

Post by Bancakes » Sun, May 02, 2021, 11:54 AM UTC

Wish normal people witnessed how few innovations are being introduced on the CPU/GPU side in the 21st century. The high-performance software industry is low-key carrying the hardware architecture industry on its back. Shaders, pipelines, coroutines, etc are there to make the programmer's job easier in the end.

On my old nokia 3110c, I could access my calendar and appointments instantly by clicking right on the d-pad. On my Nokia Lumia 710, I had to wait for a splash screen. On my Nokia 3.1, I had to wait for internet synching. The difference between slow and fast software far outstretches that of slow and fast hardware.

Re: The compiler will optimize that away

#64

Post by pif » Sun, May 02, 2021, 11:57 AM UTC

Bullshit!

The most important feature for the utter most of enterprise software is to be maintainable over requirement, managing and employee changes.

Such optimizations as those described in the article make sense only in a handful of situations, and using them must not be a light-heart decision, because their cost is big.

I fully agree with going all in when it makes sense, but we all know what is the root of all evil.

Re: The compiler will optimize that away

#65

Post by jefftk » Sun, May 02, 2021, 12:08 PM UTC

It's not a fun language to work in, but SQL does a lot of what the author is asking for.

Re: The compiler will optimize that away

#66

Post by bvrmn » Sun, May 02, 2021, 12:59 PM UTC

bsdubernerd wrote: post #46

bvrmn wrote: post #6

> 4. Data oriented way of programming has its own set of problems. This should be a top reason. Author is too shy to reveal the true cause.

Data-oriented programming is not hard by itself, rather as a consequence of how programming is done and what sort of flexibility you get in return. The traditional (or should I call "inverse") approach is to define what the program should do and make it modular enough so that parts can be changed easily. For this to work well, functions are given a state snapshot to read/operator or change. Encapsulating this state i…

I have experience with performant cache-friendly code. Yes, data oriented approach can be useful in some fields. But author blames the whole industry having low demand of performant code and wants python to accommodate cache-friendliness. This is a high level BS.

Re: The compiler will optimize that away

#67

Post by mhh__ » Sun, May 02, 2021, 1:06 PM UTC

TazeTSchnitzel wrote: post #33

The metaprogramming available in languages like Rust and C++ could maybe be leveraged to make the struct-of-arrays model easier. Wouldn't be the same as native support, though.

I've seen this done in D fairly easily, almost definitely closed source unfortunately.

Re: The compiler will optimize that away

#68

Post by CodeArtisan » Sun, May 02, 2021, 1:10 PM UTC

aparsons wrote: post #4

theamk wrote: post #2

Summary: the computer has changed -- memory latency measured in CPU cycles has grown a lot. So we should not be using traditional struct/class-like programming model, where we put all properties of an object next to each other. Instead, we should be using game-style "data oriented programming" a.k.a. "column databases" for a much higher performance. However, most modern languages (C, C++, Python, Java, etc..) are not…

What do you mean by game-style here? I’m very intrigued. Any place to read more about these?

https://gameprogrammingpatterns.com/component.html

https://gameprogrammingpatterns.com/data-locality.html

Re: The compiler will optimize that away

#69

Post by divs1210 » Sun, May 02, 2021, 1:16 PM UTC

beagle3 wrote: post #45

lordnacho wrote: post #13

Good article. My own thinking when coding performance is also towards data oriented approaches. For example Bevy in Rust. If stuff needs to be fast, it needs to be in cache. To do that, have everything nicely packed so you only ask for a chunk as often as you need. Then when you need it, it's already there. Thing about old fashioned OO is it's often fine enough for your run-of-the-mill CRUD app. If you look at the la…

> Somehow over the years I've found that the animals/cars analogies given in OO tutorials are one of the few places that fit well with the model. Yes, and I've never actually needed to implement a cat or a cow in any project :) The other thing for which OO works much better than plain data is GUIs - and I think it is not a coincidence that OO popularity exploded together with the the coming-of-age of GUIs. The other…

> The other thing for which OO works much better than plain data is GUIs

This cannot be further from my experience. Switching from Java/AWT/Swing to ClojureScript/Reagent/Re-frame has been suoer liberating.

Every GUI programmer must fiddle with reagent once:

https://reagent-project.github.io/

Re: The compiler will optimize that away

#70

Post by tom_mellior » Sun, May 02, 2021, 1:20 PM UTC

beagle3 wrote: post #49

tom_mellior wrote: post #40

Earlier quoted context omitted.

> However, most modern languages (C, C++, Python, Java, etc..) are not making it easy, The article shows how easy it is to declare a struct of arrays in Java: You declare a struct (class). Inside it you declare arrays. Done.

It is easy to declare, but it is not easy to use: You can pass the whole thing, but if you want to pass a subset of it? just one element? When you want to extend it, you have to extend many individual arrays, etc. When you want to copy entry 17 to entry 50, you can't loop over the fields - you have to spell out every field.

A subset of an AntColony is another AntColony containing sub-arrays. One element of an AntColony is an Ant which you can instantiate with the data at the appropriate index from each array. I'm not trying to be difficult, I really don't see the problem with implementing these basic programming tasks.

I agree that spelling out the fields can become tedious if you have a lot of structures of arrays or lots of fields per structure. A 100-line Python script can generate all this code for you if you prefer. Sure, it's a "limitation" of most programming languages that they don't provide this out of the box. But not a big limitation, I'd argue. Many languages even have features that allow you to write this functionality as a library, 100% inside the language (Python and Java annotations, for example).