- Some graph structures. The shared_ptr does not release circular data structures and has a lot of memory overhead. - Memory managing of concurrent containers.

- Some graph structures. The shared_ptr does not release circular data structures and has a lot of memory overhead. - Memory managing of concurrent containers. Lock-free algorithms requires GC or the hazard pointers and these are basically based on GC. - You often need the GC engine when you implementing or integrating another language.