Hacker News Reader

Comment by hashmash | Hacker News Reader

My understanding is that garbage collection in D is performed by a "stop the world" non-generational collector. Although GC is optional in D, without a more competitive implementation, the safest thing is to never depend on it. What advantage does D then have over languages like Rust and Zig?

View on HN

D's garbage collector is quite safe. Most non-trivial programs use a mix of stack allocation, RAII, malloc-style allocation, and GC. Each style has aspects they're best at.

GC is particularly well-suited when using compile time function evaluation, which executed D code at compile time (i.e. adanced constant folding, where functions can be called).

My remark regarding "safety" wasn't with respect to the quality or correctness of the implementation. My concern is the case where you've found yourself in a situation where you're relying too much on GC, and the application is experiencing long pauses. Changing the design to rely more on manual allocation is one way out, but having more GC choices would be nice too.

C/C++ interop and easy static linking makes it super nice for writing small utilities IMO

Are there GC's that doesn't halt the execution actively in use?

Java's ZGC and Shenandoah collectors suspend threads only briefly -- less than one millisecond regardless of the heap size.

How come more languages doesn't implement non-halting GC?

The garbage collector must lock threads if it is compacting or does not create separate stacks for pointers only. All GCs for Java a lock application threads.

There is only one like that, SGCL for C++ https://github.com/pebal/sgcl

Reply on news.ycombinator.com