C# it's plenty fast for game programming.

The developers of Risk of Rain 2 were undoubtedly aware of the hitches, but it interfered with their vision of the game, and affected users were left with a degraded experience.

It's worth mentioning that when game developers scope of the features of their game, available tech informs the feature-set. Faster languages thus enable a wider feature-set.

In this game's case though they possibly didn't do much optimization to reduce GC by pooling, etc. Unity has very good profiling tools to track down allocations built in so they could have easily found significant sources of GC allocations and reduced them. I work on one of the larger Unity games and we always profile and try to pool everything to reduce GC hitches.

This is true, but developer productivity also informs the feature set.

A game could support all possible features if written carefully in bare metal C. But it would take two decades to finish and the company would go out of business.

Game developers are always navigating the complex boundary around "How quickly can I ship the features I want with acceptable performance?"

Given that hardware is getting faster and human brains are not, I expect that over time higher level languages become a better fit for games. I think C# (and other statically typed GC languages) are a good balance right now between good enough runtime performance and better developer velocity than C++.

They probably create too much garbage. It’s equally easy to slow down C++ code with too many malloc/free functions called by the standard library collections and smart pointers.

The solution is the same for both languages: allocate memory in large blocks, implement object pools and/or arena allocators on top of these blocks.

Neither C++ nor C# standard libraries have much support for that design pattern. In both languages, it’s something programmers have to implement themselves. I did things like that multiple time in both languages. I found that, when necessary, it’s not terribly hard to implement that in either C++ or C#.

I think this is where the difference between these languages and rust shines - Rust seems to make these things explicit, C++/C# hides behind compiler warnings.

Some things you can't do as a result in Rust, but really if the rust community cares it could port those features (make an always stack type type, e.g.).

Code base velocity is important to consider in addition to dev velocity, if the code needs to be significantly altered to support a concept it swept under the rug e.g. object pools/memory arenas, then that feature is less likely to be used and harder to implement later on.

As you say, it's not hard to do or a difficult concept to grasp, once a dev knows about them, but making things explicit is why we use strongly typed languages in the first place...

GC can work or not when writing a game engine. However everybody who writes a significant graphical game engine in a GC language learns how to fight the garbage collector - at the very least delaying GC until between frames. Often they treat the game like safety critical: preallocate all buffers so that there is no garbage in the first place (or perhaps minimal garbage). Without garbage collection might technically use more CPU cycles, but in general they are spread out more over time and so more consistent.

AFAIK it has been possible to replace the GC with alternative implementation for the past few years, but no one has made one yet.

EDIT: Some experimental alternative GC implementations:

https://github.com/kkokosa/UpsilonGC

https://www.codeproject.com/Articles/5372791/Implementing-a-...

Unity used Mono. Which wasn't the best C# implementation, performance wise. After Mono changed its license, instead of paying for the license, Unity chose to implement their infamous IL2CPP, which wasn't better.

Now they want to use CoreCLR which is miles better than both Mono and IL2CPP.

Would be nice to hear about a Rust Game engine, though.

Also, if you invoke GC intentionally at convenient timing boundaries (I.e., after each frame), you may observe that the maximum delay is more controllable. Letting the runtime pick when to do GC is what usually burns people. Don't let the garbage pile up across 1000 frames. Take it out every chance you get.

Manually invoking GC many times per second is a viable approach?

You're basically trading off worse throughput for better latency.

If you forcibly run the GC every frame, it's going to burn cycles repeatedly analyzing the same still-alive objects over and over again. So the overall performance will suffer.

But it means that you don't have a big pile of garbage accumulating across many frames that will eventually cause a large pause when the GC runs and has to visit all of it.

For interactive software like games, it is often the right idea to sacrifice maximum overall efficiency for more predictable stable latency.

It might be more useful to use OSU! approach as a reference: https://github.com/dotnet/runtime/issues/96213#issuecomment-...

OSU! represents an extreme case where the main game loop runs at 1000hz, so for much more realistic ~120hz you have plenty of options.

Magic, code or otherwise, sucks when the spell/library/runtime has different expectations than your own.

You expect levitation to apply to people, but the runtime only levitates carbon based life forms. You end up levitating people without their affects (weapons/armor), to the embarrassment of everyone.

There should be no magic, everything should be parameterized, the GC is a dangerous call, but it should be exposed as well (and lots of dire warnings issued to those using it).

If you have a bunch of objects in an array that you have a reference to such that you can pass it, then, by definition, those objects are not garbage, since they're still accessible to the program.

There should be some middle ground between RAII and invoking Dispose/delete and full blown automatic GC.

BUT it's definitely not a language designed for no-gc so there are footguns everywhere - that's why Rider ships special static analysis tools that will warn you about this. So you can keep GC out of your critical paths, but it won't be pretty at that point. But better than Java :D

Possibly prettier than C and C++ still. Every time I write something and think "this could use C" and then I use C and then I remember why I was using C# for low-level implementation in the first place.

It's not as sophisticated and good of a choice as Rust, but it also offers "simpler" experience, and in my highly biased opinion pointers-based code with struct abstractions in C# are easier to reason about and compose than more rudimentary C way of doing it, and less error-prone and difficult to work with than C++. And building final product takes way less time because the tooling is so much friendlier.

> Unity devs run into

So it's viable but not perfect

They also have a C# subset called Burst, which could have been avoided if they were using .NET Core.

The article discusses ref lifetime analysis that does have relationship with GC, but it does not force you into using one. Byrefs are very special - they can hold references to stack, to GC-owned memory and to unmanaged memory. You can get a pointer to device mapped memory and wrap it with a Span<T> and it will "just work".

You have to jump through some hoops but it's really not that convoluted and miles easier than good C++.

I wish there was an attribute in C# that was "[MustNotAllocate]" which files the compilation on known allocations such as these. It's otherwise very easy to accidentally introduce some tiny allocation into a hot loop, and it only manifests as a tiny pause after 20 minutes of runtime.

That being said, .NET includes lots of performance-focused analyzers, directing you to faster and less-allocatey equivalents. There surely also is one on NuGet that could flag foreach over a class-based enumerator (or LINQ usage on a collection that can be foreach-ed allocation-free). If not, it's very easy to write and you get compiler and IDE warnings about the things you care about.

At work we use C# a lot and adding custom analyzers ensuring code patterns we prefer or require has been one of the best things we did this year, as everyone on the team requires a bit less institutional knowledge and just gets warnings when they do something wrong, perhaps even with a code fix to automatically fix the issue.

Even when allocations happen, .NET is much more tolerant to allocation traffic than, for example, Go. You can absolutely live with a few allocations here and there. If all you have are small transient allocations - it means that live object count will be very low, and all such allocations will die in Gen 0. In scenarios like these, it is uncommon to see infrequent sub-500us GC pauses.

Last but not least, .NET is continuously being improved - pretty much all standard library methods already allocate only what's necessary (which can mean nothing at all), and with each release everything that has room for optimization gets optimized further. .NET 9 comes with object stack allocation / escape analysis enabled by default, and .NET 10 will improve this further. Even without this, LINQ for example is well-behaved and can be used far more liberally than in the past.

It might sound surprising to many here but among all GC-based platforms, .NET gives you the most tools to manage the memory and control allocations. There is a learning curve to this, but you will find yourself fighting them much more rarely in performance-critical code than in alternatives.

IL2CPP, Unity's C# to C++ compiler, does not help for any of this. It just allows Unity to support platforms where JIT is not allowed or possible. The GC is the same if using Mono or IL2CPP. The performance of code is also roughly identical to Mono on average, which may be surprising, but if you inspect the generated code you'll see why [2].

[1] https://xoofx.github.io/blog/2018/04/06/porting-unity-to-cor... [2] https://www.jacksondunstan.com/articles/4702 (many good articles about IL2CPP on this site)

https://discussions.unity.com/t/coreclr-and-net-modernizatio...

It's really not that hard to structure a game that pre-allocates and keeps per frame allocs at zero.

I have been learning F# for a while now, and while the functional side that is pushed heavily is a joy to use, anything that touches the 'outside world' is going to have way more resources for C# as far as libraries, official documentation, general information including tutorials etc. You will need to understand and work with those.

So you really do need to understand C# syntax and semantics. Additionally there are a few concepts that seem the same in each language but have different implementations and are not compatible (async vs tasks, records) so there is additional stuff to know about when mentally translating between C# and F#.

I really want to love F# but keep banging my head against the wall. Elixir while not being typed yet and not being as general purpose at least allows me to be productive with it's outstanding documentation, abundance of tutorials and books on both the core language and domain specific applications. It is also very easy to mentally translate erlang to elixir and vice versa in the very few occasions needed.

Yeah. What's your opinion on Gleam?

The flipside is that adopting F# is less risky as a result - if there isn't a library or you are stuck you can always bridge to these .NET libraries. Its similar I think with other shared runtime languages (e.g. Scala, Kotlin, Clojure, etc). You do need to understand the ecosystem as a whole at some point and how it structures things.

While it's good to have the escape hatch; because it means its less of a risk to adopt F# (i.e. you will always have the whole .NET ecosystem at your finger tips) if the C# framework being adopted is complex (e.g. uses a lot of implicits) it requires good mentoring and learning to bridge the gap and usually at this point things like IDE support, mocking, etc that weren't needed as much before are needed heavily (like a typical C# code base). Many C# libraries are not that easy therefore IMO, but with C# native templates, etc it becomes more approachable if coming from that side.

I've found things like the differences in code structure, the introduction of things like patterns (vs F#'s "just functions" ideal), dependency injection, convention based things (ASP.NET is a big framework with lots of convention based programming) and other C# things that F# libraries would rather not have due to complexity is where people stumble. Generally .NET libraries are easy in F# - its frameworks that are very OOP that make people outside the C#/Java/OOP ecosystem pause a bit at least in my experience. There's good articles around libraries vs frameworks in the F# space if I recall illustrating this point.

To ease the wait you could try Dunet (discriminated union source generator).

https://github.com/domn1995/dunet

Practical example in a short write up here: https://chrlschn.dev/blog/2024/07/csharp-discriminated-union...

if building for the web online, asp.net core runs on Linux servers as well as windows

and there's MAUI [2] ( not a fan of this), you are better-off with with the others.

in summary c# and .NET is cross-platform, third party developers build better frameworks and tools for other platform while Microsoft prefers to develop for Microsoft ecosystem, if you get

[0] https://avaloniaui.net/ [1] https://platform.uno/ [2] https://learn.microsoft.com/en-us/dotnet/maui/what-is-maui?v...

I will say MS has been obsessed with trying to take a slice of the mobile pie.

However their Xamarin/WPF stuff left so much to be desired and was such a Jenga Tower that I totally get the community direction to go with a framework you have ostensibly have more control over vs learning that certain WPF elements are causes of e.g. memory leaks...

I work at one of the few startups that uses C# and .NET.

Dev machines are all M1/M3 MacBook Pros and we deploy to a mix of x64 and Arm64 instances on GCP and AWS.

I use VS Code on macOS while the rest of the team prefers Rider.

Zero friction for backend work and certainly more pleasant than Node. (We still use Node and JS for all front-end work).

.NET has some small cross platform abilities, but calling it totally cross platform is wrong.

In fairness this ignores a lot of embedded work.

Java gets to cheat here a bit because they have some custom embedded stuff, but they are also not actually running on all CPUs.

(Jk I love C#)

Operating Systems: Linux, macOS, Windows, FreeBSD, iOS, Android, Browser

Architectures: x86, x86_64, ARMv6, ARMv7, ARMv8/ARM64, s390x, WASM

Notes:

Mono as referred here means https://github.com/dotnet/runtime/tree/main/src/mono which is an actively maintained runtime flavor, alongside CoreCLR.

- Application development targets on iOS and Android use Mono. Android can be targeted as linux-bionic with regular CoreCLR, but it's pretty niche. iOS has experimental NativeAOT support but nothing set in stone yet, there are similar plans for Android too.

- ARMv6 requires building runtime with Mono target. Bulding runtime is actually quite easy compared to other projects of similar size. There are community-published docker images for .NET 7 but I haven't seen any for .NET 8.

- WASM also uses Mono for the time being. There is a NativeAOT-LLVM experiment which promises significant bundle size and performance improvements

- For all the FreeBSD slander, .NET does a decent job at supporting it - it is listed in all sorts of OS enums, dotnet/runtime actively accepts patches to improve its support and there are contributions and considerations to ensure it does not break. It is present in https://www.freshports.org/lang/dotnet

At the end of the day, I can run .NET on my router with OpenWRT or Raspberry Pi4 and all the laptops and desktops. This is already quite a good level given it's completely self-contained platform. It takes a lot of engineering effort to support everything.

Mono was a third party glorified hack to get C# to work on other OS. .NET has been natively cross platform with an entirely new compiler and framework since mid 2016.

Indeed, this is what I didn't like back then. Java has official support for other OSes, which C# was lacking at the time. Good to hear that things changed now.

.NET has moved to being directly cross-platform today and is great at server/console app cross-platform now, but its support for cross-platform UI is still relatively nascent. The official effort is called MAUI, has mostly but not exclusively focused on mobile, and it is being developed in the open (as open source does) and leaves a lot to be desired, including by its relatively slow pace compared to how fast the server/console app cross-platform stuff moves. The Linux desktop support, specifically, seems constantly in need of open source contributors that it can't find.

You'll see a bunch of mentions of third-party options Avalonia and Uno Platform doing very well in that space, though, so there is interesting competition, at least.

There's a lot of options, but also the latest of .NET (not Framework) just runs natively on Linux, Mac and Windows, and there's a few open source UI libraries as mentioned by others like Avalonia that allow your UI to run on any OS.

I assume you mean just the Windows Visual Studio? The Mac version is not exactly on par with the Windows. Yeah C# is great, but one would need Window's version of VS (NOT VS Code) to take full advantage of C#. For me that is a deal breaker, when the DX of a language is tight to a proprietary sourced IDE by MS.

https://blog.jetbrains.com/blog/2024/10/24/webstorm-and-ride...

[edit: I’ll note I’ve used successfully both Win and Linux]

So it seems at least that part of your critique is outdated.

I'm not sure what you mean about the inference, I've never had any problem with that that I can remember. And it can be a bit slow to start up or analyze a project at first load but in return it gives much better code completion and such.

if (s is string or s is int) { // what's the type of s here? is it "string | int" ? }

And not to mention that the BCL should probably get new overloads using DU's for some APIs. But there is at least a work in progress now, after years of nothing.

No, it isn't. The power of C++ templates is still astronomically far from C# generics.

Haskell promises to solve concurrency and the Rust boys are always claiming that it's impossible to write buggy code in Rust.. and the jump from C/C++/C#/Golang to Rust is much smaller than to Haskell..

Oh that's what I was getting at, that makes Rust pretty much a must-have tool to have in your tool-belt.

It's good that it is now, but how can it be implemented in a way that has truly separate instantiations of generics at runtime, when calls cross assembly boundaries? There's no single good place to generate a specialization when virtual method body is in one assembly while the type parameter passed to it is a type in another assembly.

There are no assembly boundaries under NativeAOT :)

Even with JIT compilation - the main concern, and what requires special handling, are collectible assemblies. In either case it just JITs the implementation. The cost comes from the lookup - you have to look up a virtual member implementation and then specific generic instantiation of it, which is what makes it more expensive. NativeAOT has the definitive knowledge of all generic instantiations that exist, since it must compile all code and the final binary does not have JIT.

I'm not a templates/macro guy so I'm curious what's missing.

Sorry for the snark, but I do think C# compile are just barely acceptable for me, so I'm happy they aren't adding more heavy compile time features.

No! It misses "typedef", both at module API level and within generics.

I wish Anders was still in charge of C# :(

In order to submit bugs with Microsoft the application redirects the end user to their website with web socket. The company I work for has extra security and this breaks preventing me from filing a cornucopia of bugs with Visual Studio. I cannot even file a bug on how the submit system is broken with Visual Studio.

Closing and re-opening Visual Studio is a daily task. Most often during code refactoring of multiple parts. Creating new classes has inconsistency of template usage in the second most recent released version. Compile error message history can become stale and inconsistent where the output console does not. Pasting content into the resource manager is still broken during tab entry. Modal dialogs still cover the screen during debug. And those don't even touch the inconstant and buggy user experience.

C# is a tool and like all tools it is good for some things and really bad for others. No tool is perfect. You can still use a ball-peen hammer for roofing but be better to have a roofing hammer. I would use Swift on iOS and Kotlin on Android for those platform projects, I don't even know those languages, and wouldn't use C#.