Completing the pidfd API

Does this get rid of some shared data-structure in the kernel that maps PIDs to the actual resources of the process? I ask because I noticed that with pthreads one can write "pthread_detach(pthread_self())" to detach yourself, whereas presumably detaching yourself via a pidfd you got from "yourself" would be a no-op as any resources would be held open by the other pidfd opened by your parent thread. I noticed this when implementing pthreads/c11 threads on windows, where threads are represented by HANDLES that are recounted and work similarly to files. On windows I came to the conclusion that allowing threads to detach themselves would require a shared data-structure holding the mapping of PIDs to HANDLES.