Re: Shortening the Scope of Critical Section in Creation of New MultiXacts

Hello.

In short, the code as-is looks correct.

At Wed, 14 Dec 2022 00:14:34 +0000, "Bagga, Rishu" <bagrishu(at)amazon(dot)com> wrote in
> * Critical section from here until caller has written the data into the
> * just-reserved SLRU space; we don't want to error out with a partly

"the data" here means the whole this multi transaction, which includes
members. We shouldn't exit the critical section at least until the
very end of RecordNewMultiXact().

> This makes sense, as we need the multixact state and multixact offset
> data to be consistent, but once we write data into the offsets, we can
> end the critical section. Currently we wait until the members data is
> also written before we end the critical section.

Why do you think that the members are not a part of a
multitransaction? A multitransaction is not complete without them.

Addition to the above, we cannot simply move the END_CRIT_SECTION() to
there since RecordNewMultiXact() has another caller that doesn't start
a critical section.

By the way, I didn't tested this for myself but..

> This passes regression tests

Maybe if you did the same with an assertion-build, you will get an
assertion-failure.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center