> -----Original Message----- > From: Tom Lane <tgl@xxxxxxxxxxxxx> > Sent: Sunday, August 22, 2021 15:24 > To: ldh@xxxxxxxxxxxxxxxxxx > Cc: Justin Pryzby <pryzby@xxxxxxxxxxxxx>; Ranier Vilela > <ranier.vf@xxxxxxxxx>; pgsql-performance@xxxxxxxxxxxxxx > Subject: Re: Big Performance drop of Exceptions in UDFs between V11.2 > and 13.4 > > "ldh@xxxxxxxxxxxxxxxxxx" <ldh@xxxxxxxxxxxxxxxxxx> writes: > > So, now, in summary: > > > - I have tried V13.4, V12.3, 11.13, 11.2, 11.1 on several Windows VMs > and my personal laptop (no VM). > > - All V11.x seem to behave uniformly. > > - Starting with 12.3, I am experiencing the major slowdown in the > "with exceptions" scenario. > > Interesting. There's no meaningful difference between v11 and v12 as > far as timeout handling goes, so I'm starting to think that that's a red > herring. > > (Although, after having done some web-searching, I do wonder why > timer.c is using a manual-reset event. It looks like auto-reset would > work just as well with less code, and I found some suggestions that it > might perform better.) > > > So, I was thinking about stuff and a lot of your intuitions seem to drive > towards an issue with the compiler used to compile the Winx64 > version... But is it possible that the JIT is getting in there and making > things weird? Given that it's a major change in V12 and this is when I am > starting to see the issue popup, I figured it might be another avenue to > look into? > > Hm, is JIT even enabled in your build? If so, does setting jit = 0 change > anything? > > regards, tom lane Hello Tom, I just ran the test with jit=off in the config and restated the server. No change on 13.4. I'd think that the query cost as per the planner would be too small to kick in the JIT but thought to check anyways. Doesn't seem to be the cause. Thanks., Laurent.
