Then don't do that part, allocate at the end and only rewrite existing blocks rather than deleting them. It's like how just because you can't easily sbrk(2) ne

Then don't do that part, allocate at the end and only rewrite existing blocks rather than deleting them. It's like how just because you can't easily sbrk(2) new memory before at the beginning of a heap doesn't mean you can't have multiple threads despite that being the resource you're contending.