> > > You never need to reduce it to a shared lock. On postmaster startup, > > > try to lock the sentinel byte (one byte past the end-of-file). If you > > > can lock it, you know that no other postmaster has that byte locked. If > > > you can't lock it, another postmaster is running. It is an atomic > > > operation. > > > > This doesn't work if the postmaster dies but a backend continues to run, > > which is arguably the most important case we need to protect against. > > I may be confused here, but I don't see the problem - byte-range locks > are not inherited across a fork. A backend would never hold the lock, a > backend would never even look for the lock. Well, you are wrong here. We _want_ every backend to hold a shared lock. We need to stop a postmaster from starting if there is a backend running that was started by a no-longer-running postmaster.
Oh... didn't know that. How is that accomplished now? There must be some code beside the pid file check.
-- Korry
