Re: Connections hang indefinitely while taking a gin index's LWLockbuffer_content lock

Hi,

On 2018-12-13 22:40:59 +0300, Alexander Korotkov wrote:
> It doesn't mater, because we release all locks on every buffer at one
> time.  The unlock order can have effect on what waiter will acquire
> the lock next after ginRedoDeletePage().  However, I don't see why one
> unlock order is better than another.  Thus, I just used the rule of
> thumb to not change code when it's not necessary for bug fix.

I think it's right to not change unlock order at the same time as a
bugfix here.  More generally I think it can often be useful to default
to release locks in the inverse order they've been acquired - if there's
any likelihood that somebody will acquire them in the same order, that
ensures that such a party would only need to wait for a lock once,
instead of being woken up for one lock, and then immediately having to
wait for the next one.

Greetings,

Andres Freund