[bad_user]

Ref counting is not deterministic. First of all because while looping on an atomic reference is non blocking, it is not wait free. Malloc/free are not deterministic either, can be quite expensive and while real-time implementations exist, that's not the malloc/free you end up using. With a generational GC allocating new objects involves just incrementing a pointer, deallocating short lived objects happens in bulk, so the cost for short-lived objects is similar to stack allocation. With ref counting memory gets fragmented, apps like Firefox have been suffering for years from fragmentation and for Firefox there was a sustained and very significant effort to fix it.

This can only be solved by either doing stack allocation or by building object pools. And this is for people that know what they are doing.

Rust is the only language (I know) that tries solving this with the ownership concept in the language, but then Rust will have problems in implementing immutable data structures that can be shared amongst threads, data structures which are doing structural sharing, so people will expect reads to scale, except there will be non-obvious contention happening due to usage of reference counting.

The latency in state of the art mainstream GCs is also NOT variable. Good garbage collectors allow you to control the max latency and frequency of STW pauses. That is not the issue for real-time requirements - the issue with real-time being that STW is unacceptable. But so is reference counting.

On the memory requirements, I don't buy it. My Android phone has more memory and more CPU capacity than my computer did 7 years ago. And I'm not seeing a difference in behavior to my iPad. Surely for games it pretty bad to drop frames, but most apps are not games and games are using highly optimized engines built in C++anyway.

[pjmlp]

> Rust is the only language (I know) ...

Have a look at Cyclone, ATS and ParaSail.