Re: [HACKERS] Moving relation extension locks out of heavyweight lock manager

On Mon, 9 Mar 2020 at 14:16, Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Sun, Mar 8, 2020 at 7:58 AM Masahiko Sawada <masahiko.sawada@2ndquadrant.com> wrote:
>> >
>> > Fair position, as per initial analysis, I think if we do below three
>> > things, it should work out without changing to a new way of locking
>> > for relation extension or page type locks.
>> > a. As per the discussion above, ensure in code we will never try to
>> > acquire another heavy-weight lock after acquiring relation extension
>> > or page type locks (probably by having Asserts in code or maybe some
>> > other way).
>>
>> The current patch
>> (v02_0001-Added-assert-to-verify-that-we-never-try-to-take-any.patch)
>> doesn't check that acquiring a heavy-weight lock after page type lock,
>> is that right?
>
>
> No, it should do that.
>
>>
>> There is the path doing that: ginInsertCleanup() holds
>> a page lock and insert the pending list items, which might hold a
>> relation extension lock.
>
>
> Right, I could also see that, but do you see any problem with that?  I agree that Assert should cover this case, but I don't see any fundamental problem with that.

I think that could be a problem if we change the group locking so that
it doesn't consider page lock type.