Re: Moving relation extension locks out of heavyweight lock manager

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Wed, May 10, 2017 at 8:39 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> ... I'd like to propose to change relation
>> extension lock management so that it works using LWLock instead.

> That's not a good idea because it'll make the code that executes while
> holding that lock noninterruptible.

Is that really a problem? We typically only hold it over one kernel call,
which ought to be noninterruptible anyway. Also, the CheckpointLock is
held for far longer, and we've not heard complaints about that one.

I'm slightly suspicious of the claim that we don't need deadlock
detection. There are places that e.g. touch FSM while holding this
lock. It might be all right but it needs close review, not just an
assertion that it's not a problem.

regards, tom lane