Date: Fri, 5 Oct 2018 15:35:04 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>,
	Sergei Kornilov <sk@zsrv.org>, nasbyj@amazon.com,
	Andres Freund <andres@anarazel.de>,
	Robert Haas <robertmhaas@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: pgsql: Improve autovacuum logging for aggressive and
 anti-wraparound ru
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On Fri, Oct 05, 2018 at 12:16:03PM +0900, Michael Paquier wrote:
> So, I have come back to this stuff, and finished with the attached
> instead, so as the assertion is in a single place.  I find that
> clearer.  The comments have also been improved.  Thoughts?

And so...  I have been looking at committing this thing, and while
testing in-depth I have been able to trigger a case where an autovacuum
has been able to be not aggressive but anti-wraparound, which is exactly
what should not be possible, no?  I have simply created an instance with
autovacuum_freeze_max_age = 200000, then ran pgbench with
autovacuum_freeze_table_age=200000 set for each table, and also ran
installcheck-world in parallel.  This has been able to trigger the
assertion pretty quickly.

Here is the stack trace:
#2  0x000055e1a12ef87b in ExceptionalCondition
 (conditionName=0x55e1a14b45c8 "!((params->is_wraparound &&
 aggressive) || !params->is_wraparound)",
     errorType=0x55e1a14b459d "FailedAssertion", fileName=0x55e1a14b4590
 "vacuumlazy.c", lineNumber=254) at assert.c:54
#3  0x000055e1a0f6c6ad in lazy_vacuum_rel (onerel=0x7f163e7ea710,
options=65, params=0x55e1a2eeba70, bstrategy=0x55e1a2f5c1a0) at
vacuumlazy.c:253
#4  0x000055e1a0f6c217 in vacuum_rel (relid=1260,
relation=0x55e1a2f5d748, options=65, params=0x55e1a2eeba70) at
vacuum.c:1714
#5  0x000055e1a0f6a3ac in vacuum (options=65, relations=0x55e1a2f2f050,
params=0x55e1a2eeba70, bstrategy=0x55e1a2f5c1a0, isTopLevel=true) at
vacuum.c:340
#6  0x000055e1a10c1ddd in autovacuum_do_vac_analyze
(tab=0x55e1a2eeba68, bstrategy=0x55e1a2f5c1a0) at autovacuum.c:3121
#7  0x000055e1a10c0e19 in do_autovacuum () at autovacuum.c:2476

$2 = {spcNode = 1664, dbNode = 0, relNode = 1260}
(gdb) p onerel->rd_node.relNode
$3 = 1260
(gdb) p params->is_wraparound
$4 = true
(gdb) p aggressive
$5 = false

I still have the core file, the binaries and the data folder, so it's
not a problem to dig into it.
--
Michael

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