Re: Max connections reached without max connections reached

> On Fri, Dec 03, 2021 at 10:32:03AM -0500, Tom Lane wrote:
> Dilip Kumar <dilipbalaut(at)gmail(dot)com> writes:
> > On Thu, Dec 2, 2021 at 9:35 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >> I think there is no such view or anything which tells about which
> >> backend or transaction has more than 64 sub transaction. But if we
> >> are ready to modify the code then we can LOG that information in
> >> GetNewTransactionId(), when first time we are marking it overflown.
>
> > I have prepared a small patch to log this information.
>
> Putting an elog call into GetNewTransactionId seems like a completely
> horrid idea from a performance standpoint. Especially if you put it
> inside the XidGenLock hold, where it can block the entire system not just
> the one process. But even without that, this seems like a performance
> penalty with basically no real-world benefit. People who have issues
> like this are not going to want to trawl the postmaster log for such
> messages.

Maybe it's worth a trace point then, to allow collect such info sort of
on demand?