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Why I Write Games in C (yes, C)

jonathanwhiting.com

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Re: Why I Write Games in C (yes, C)

#431

Post by sgtnoodle »

greggman2 wrote: post #363
bcrescimanno wrote: post #70

Earlier quoted context omitted.

Disclaimer: I'm not a game developer; but, I've worked on a lot of projects with tight frame time requirements in my time at Netflix on the TVUI team. I also have no experience in Go so I can't comment on the specifics of that garbage collector vs. V8. I don't think it's necessarily that it "can't" work as much as it takes away a critical element of control from the game developers and the times you find yourself "at…

There's probably 500+ successful GC based games on the Steam store another 100000 to a million hobby games doing just fine with GC. I started game programming on the Atari 800, Apple 2, TRS-80. Wrote NES games with 2k of ram. I wrote games in C throughout the 90s including games on 3DO and PS1 and at the arcade. I was a GC hater forever and I'm not saying you can ignore it but the fact that Unity runs in C# with GC a…

Kerbal Space Program is a lot of fun, but for me it freezes for half a second every 10 seconds... due to garbage collection. Drives me crazy.

Re: Why I Write Games in C (yes, C)

#432

Post by fileeditview »

littlestymaar wrote: post #214
zemo wrote: post #98

Earlier quoted context omitted.

as an example point, the Go garbage collector clears heaps of 18gb in sub-millisecond latencies. If I'm understanding the problem at hand (maybe I'm not!), given an engine running at a target framerate of 144 frames per second, you're working with a latency budget of about 7ms per frame. Do you always use all 7ms, or do you sometimes sleep or spin until the next frame to await user input? We can also look at it from…

> Go garbage collector clears heaps of 18gb in sub-millisecond latencies At the expense of a lot of work from the GC. In production we had 30% of the usage coming from the GC alone… But for game development the problem isn't going to be the GC anyway: cgo is just not adapted to this kind of tasks (and you cannot avoid cgo here).

Best comment here. I have spent some time evaluating Go for making games. Considering the fact that for 95% of games it doesn't really matter if the language has a GC it could have been a very nice option.

Currently CGO just sucks. It adds a lot of overhead. The next problem is target platforms. I don't have access to console SDKs but compiling for these targets with Go should be a major concern.

Go could be a nice language for making games but with the state it is in the only thing is good for is hobby desktop games.

Re: Why I Write Games in C (yes, C)

#433

Post by littlestymaar »

xyproto wrote: post #271
littlestymaar wrote: post #220

Earlier quoted context omitted.

You're not using the GC at all then. Why use Go (and praise its GC) in that case?

Go has many advantages over C that are not related to GC.

In a context where you don't allocate memory, you lose a lot of those (for instance, you almost cannot use interfaces, because indirect calls cause parameters to those calls to be judged escaping and unconditionally allocated on the heap).

Go is a good language for web backend and other network services, but it's not a C replacement.

Re: Why I Write Games in C (yes, C)

#434

Post by fileeditview »

inimino wrote: post #289
zemo wrote: post #288

Earlier quoted context omitted.

you can turn off the gc in Go and run it manually. you can also write cache-aligned arrays of structs in Go if you want to. you can allocate a slab and pull from it if you want to. the existence of a GC doesn't preclude these possibilities.

Why pick a language that has a feature you need to immediately turn off? Some people probably want to, but ... why?

I guess you use every feature (insert any language here) offers for every program you write with it?

The answer to your question is probably: because they like the language, are productive in it, know the libraries and the feature can be turned off so it's an option.

Re: Why I Write Games in C (yes, C)

#435

Post by ncmncm »

correct_horse wrote: post #283
mlthoughts2018 wrote: post #227

Earlier quoted context omitted.

Doesn’t this just change semantics? Whatever custom handlers you wrote for manipulating that big chunk of memory are now the garbage collector. You’re just asking for finer grained control than what the native garbage collection implementation supports, but you are not omitting garbage collection. Ostensibly you could do the exact same thing in e.g. Python if you wanted, by disabling with the gc module and just writi…

C's free() gives memory back to the operating system(1), whereas, as a performance optimization, many GCd languages don't give memory back after they run a garbage collection (see https://stackoverflow.com/questions/324499/java-still-uses-s... ). Every Python program is using a "custom allocator," only it is built in to the Python runtime. You may argue that this is a dishonest use of the term custom allocator, but c…

Freeing memory to the OS causes TLB cache stalls in all other threads in the process.

If the program runs for any length of time, it will probably need the same memory again, so freeing it is a pessimization.

Standard C library free() implementations very, very rarely free memory back to the OS.

Re: Why I Write Games in C (yes, C)

#436

Post by abainbridge »

jcelerier wrote: post #416
Pombal wrote: post #401

Earlier quoted context omitted.

You are describing 'zero cost abstractions'. Except that they are anything but zero cost. Game developers and low level programmers shy away from them because of their impact in compile and build times, debug build performance and stack trace bloat, increased cognitive load, reduced refactoring ability. Even std::unique_ptr has runtime costs in release builds that a raw pointer does not. In game development performan…

> Even std::unique_ptr has runtime costs in release builds that a raw pointer does not. O RLY ? https://gcc.godbolt.org/z/QhbUjI

How would I create the pointer to int in the unique_ptr case without initializing the int? I tried this: https://gcc.godbolt.org/z/SfVxzU

I expect there is a way, just I don't know it.

Re: Why I Write Games in C (yes, C)

#437

Post by nearbuy »

forrestthewoods wrote: post #101
zemo wrote: post #46

> The stop-the-world garbage collection is a big pain for games, stopping the world is something you can't really afford to do. I love this opinion from games programmers because they never qualify it and talk about what their latency budgets are and what they do in lieu of a garbage collector. They just hand wave and say "GC can't work". The reality is you still have to free resources, so it's not like the garbage c…

> I love this opinion from games programmers because they never qualify it and talk about what their latency budgets are and what they do in lieu of a garbage collector. Bro, game devs talk about this non-stop. There are probably 1000 GDC talks about memory management. Game devs don't spell the fine details because they are generally talking to other game devs and there is assumed knowledge. Everyone in games knows a…

Unity is frustrating because the regular C# CLR (and Mono) have a much better generational GC with fast Gen 0 and Gen 1 collections. Unity's crappy GC is always slow.

Re: Why I Write Games in C (yes, C)

#438

Post by exDM69 »

sgtnoodle wrote: post #431
greggman2 wrote: post #363

Earlier quoted context omitted.

There's probably 500+ successful GC based games on the Steam store another 100000 to a million hobby games doing just fine with GC. I started game programming on the Atari 800, Apple 2, TRS-80. Wrote NES games with 2k of ram. I wrote games in C throughout the 90s including games on 3DO and PS1 and at the arcade. I was a GC hater forever and I'm not saying you can ignore it but the fact that Unity runs in C# with GC a…

Kerbal Space Program is a lot of fun, but for me it freezes for half a second every 10 seconds... due to garbage collection. Drives me crazy.

Even on a fast PC, Kerbal Space Program audio is choppy because of GC pauses.

It's successful in spite of that, but that doesn't make it any better.

Re: Why I Write Games in C (yes, C)

#439

Post by ncmncm »

oppositelock wrote: post #297
yellowapple wrote: post #262

Earlier quoted context omitted.

> use exceptions instead of return code for errors I happen to have the exact opposite opinion. Exception handling tends to feel too "magical" (read: non-deterministic, hard to behaviorally predict, etc.) relative to just returning an error code.

Exception handling doesn't work very well. It requires exception frames on the stack, and those go missing sometimes, leading to leaked exceptions and unexpected crashes. For example, if you pass a C++ callback function into a C callback, say in libcurl, the C library doesn't have exception handler frames in the stack, so exceptions are lost. If your C++ code throws from within that C callback, any catch above the C…

Don't pass functions to libcurl that throw.

Otherwise, exceptions make code simpler, cleaner, and more reliable. They will never "go missing" unless you do something to make them go missing. Code that does those things is bad code. Don't write bad code. Do use exceptions.

Re: Why I Write Games in C (yes, C)

#440

Post by jayd16 »

wruza wrote: post #380
jayd16 wrote: post #327

Earlier quoted context omitted.

>worst side of gc is that it is unpredictable This is simply not the case. Its still just code after all. The problem was you were fighting the GC but that's just the symptom. The clear problem was leaking something every frame. With all the tooling these days its pretty easy to see exactly what is getting allocated and garbage collected so you know where to focus your efforts.

I started with C actually, but good ui is hard, and I decided to use Lua for a reason of not writing it all in C and hand-optimized style. I was forced to write ugly non-allocating code anyway, which defeated that idea completely. To focus your efforts, there must be a reason for these efforts in the first place.

But you must understand that lots of games are able to make this work. Call of Duty, for example, uses Lua for its UI scripting and is able to hit framerate. WoW uses Lua as well. Its not impossible or even impractical. There's plenty of reason to use a higher level language even if your core loops are hand optimized.
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