Robert Haas <robertmhaas@gmail.com> writes:
> There is some amount of user code (I'm not sure preceisely how much)
> that runs after shared memory is mapped and before the deadman switch
> is engaged.
Er ... what would you define as "user code"?
The deadman switch is engaged at the point where we create a PGPROC.
Before that, it's entirely impossible to take either LWLocks or
heavyweight locks, which means that practically any access to shared
memory would be illegal anyway. If there's anything very interesting
going on in that stretch, I'd be surprised.
regards, tom lane