I searched for about six weeks how to fix that and it disappeared when I changed the position of the program’s data segment.

So it was a linker issue? I wouldn’t call that undefined behaviour in multithreaded code.

But industry is still working with a fifty year old language written for systems where 32 kilobytes were a lot of memory.

Especially for embedded and DSP stuff there are so many architectures that aren’t even supported by the Rust compiler. And on those systems 32 kiB of RAM is sometimes a lot of memory.