> Garbage collection becomes almost a necessity when you have enormous concurrency and parallelism.

No, you can just use Rust, which provides thread safety without garbage collection.

Pretty much any malloc/free worth even considering using has thread-local arenas. On top of that, you can always go with custom allocators (such as bump pointer arenas) with C/C++. There's no issue scaling across dozens or hundreds of CPU cores here. Heck, the most parallel of all parallelization in computing, GPU compute, regularly uses C/C++ as the source language.

Go, on the other hand, does have scaling issues. So do most GC'd languages in fact, as the GCs want to periodically park all threads to walk their stacks. Even the latest & greatest GCs, like Shenandoah, still gotta park all them threads periodically for milliseconds at a time.

I have the opposite experience. It is considerably easier to write performant and scalable parallel program in unsafe language like C or C++, with libraries for parallel containers, than in Rust or even Go. Of course the price we pay is that it is much more probable to have bugs.

Anything realtime will be either C or C++. Audio dev for example.

Bitwig (the DAW) has a Java GUI but the core engine is C++ iirc.