Neil Conway <neilc@samurai.com> writes:
> AFAICS, that is not the case. See lwlock.c, circa line 264: in LW_SHARED
> mode, we check if "exclusive" is zero; if so, we acquire the lock
> (increment the shared lock count and do not block). And "exclusive" is
> set non-zero only when we _acquire_ a lock in exclusive mode, not when
> we add an exclusive waiter to the wait queue.
Ooh, you are right. I think that may qualify as a bug ...
regards, tom lane