I said:
> Hmm, so the point is to reclaim memory during a shmem reinit cycle?
But on third think, it doesn't do that either, and in fact is just a
waste of cycles. ShutdownBufferPoolAccess is only called in a backend
that is about to exit, and the storage you propose it should release
is local to that backend ...
So the patch appears harmless but also useless. A backend on-exit
routine is generally only interested in cleaning up state that is
visible to other backends --- I can't see any point in expending cycles
to tidy up local memory that's about to vanish.
regards, tom lane