Hi, On 2025-05-28 22:51:14 +0930, Robins Tharakan wrote: > On Tue, 20 May 2025 at 15:20, David Rowley <dgrowle...@gmail.com> wrote: > > > On Tue, 20 May 2025 at 16:07, Tom Lane <t...@sss.pgh.pa.us> wrote: > > > Failures like this one [1]: > > > > > > @@ -340,9 +340,13 @@ > > > create function myinthash(myint) returns integer strict immutable > > language > > > internal as 'hashint4'; > > > NOTICE: argument type myint is only a shell > > > +ERROR: ROWS is not applicable when function does not return a set > > > > > > are hard to explain as anything besides "that machine is quite > > > broken". Whether it's flaky hardware, broken compiler, or what is > > > undeterminable from here, but I don't believe it's our bug. So I'm > > > unexcited about putting effort into it. > > > > There are certainly much fewer moving parts in PostgreSQL code for > > that one as this failure doesn't seem to rely on anything stored in > > any tables or the catalogues. > > > > I'd have thought it would be unlikely to be a compiler bug as wouldn't > > that mean it'd fail every time? > > > > > Recently leafhopper failed again on the same test. For now I've paused it. > To rule out the compiler (and its maturity on the architecture), I'll > upgrade > gcc (to nightly, or something more recent) and then re-enable to see if it > changes anything.
+1 to a gcc upgrade, gcc 11 is rather old and out of upstream support. A kernel upgrade would be good too. My completely baseless gut feeling is that some SIMD registers occassionally get corrupted, e.g. due to a kernel interrupt / context switch not properly storing & restoring them. Weirdly enought the instrumentation code is among the pieces of PG code most vulnerable to that because we mostly don't do enough auto-vectorizable math, but InstrEndLoop(), InstrStopNode() etc are trivially auto-vectorizable. I'm pretty sure I've previously analyzed problems around this, but don't remember the details (IA64 maybe?). > I didn't dive in deeper but I see that indri failed recently [1] on what > seems > like the exact same test / line-number (at t/027_stream_regress.pl line 95) > that leafhopper has been tripping on recently. The error is not verbatim, > but it was a little too coincidental to not highlight here. For 027_stream_regress.pl you really need to look at regress_log_027_stream_regress.log, as that specific line just tests whether the standard regression tests passed. The failure on indri is rather different than your issue, I doubt there's an overlap between the problems... I think we should spruce up 027_stream_regress.pl a bit around this. Before the "regression tests pass" check we should a) check if primary is still alive b) check if standby is still alive and then, iff a) & b) pass, in addition to printing the entire regression test file, we should add the head and tail of regression.diffs to the failure message, so one can quickly glean what went wrong. Greetings, Andres Freund
