file-locking and postmaster.pid

Hi all.

I've experienced several times that PG has died somehow and the postmaster.pid
file still exists 'cause PG hasn't had the ability to delete it upon proper
shutdown. Upon start-up, after such an incidence, PG tells me another PG is
running and that I either have to shut down the other instance, or delete the
postmaster.pid file if there really isn't an instance running. This seems
totally unnecessary to me. Why doesn't PG use file-locking to tell if another
PG is running or not? If PG holds an exclusive-lock on the pid-file and the
process crashes, or shuts down, then the lock(which is process-based and
controlled by the kernel) will be removed and another PG which tries to start
up can detect that. Using the existence of the pid-file as the only evidence
gives too many false positives IMO.

I'm sure there's a good reason for having it the way it is, having so many
smart knowledgeable people working on this project. Could someone please
explain the rationale of the current solution to me?

--
Andreas Joseph Krogh <andreak(at)officenet(dot)no>
Senior Software Developer / Manager
gpg public_key: http://dev.officenet.no/~andreak/public_key.asc
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