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pgsql: Fix test races between syscache-update-pruned.spec and autovacuu 2+ messages / 1 participants [nested] [flat]
* pgsql: Fix test races between syscache-update-pruned.spec and autovacuu @ 2025-04-09 14:25 Noah Misch <noah@leadboat.com> 0 siblings, 0 replies; 2+ messages in thread From: Noah Misch @ 2025-04-09 14:25 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix test races between syscache-update-pruned.spec and autovacuum. This spec fails ~3% of my Valgrind runs, and the spec has failed on Valgrind buildfarm member skink at a similar rate. Two problems contributed to that: - A competing buffer pin triggered VACUUM's lazy_scan_noprune() path, causing "tuples missed: 1 dead from 1 pages not removed due to cleanup lock contention". FREEZE fixes that. - The spec ran lazy VACUUM immediately after VACUUM FULL. The spec implicitly assumed lazy VACUUM prunes the one tuple that VACUUM FULL made dead. First wait for old snapshots, making that assumption reliable. This also adds two forms of defense in depth: - Wait for snapshots using shared catalog pruning rules (VISHORIZON_SHARED). This avoids the removable cutoff moving backward when an XID-bearing autoanalyze process runs in another database. That may never happen in this test, but it's cheap insurance. - Use lazy VACUUM option DISABLE_PAGE_SKIPPING. Commit c2dc1a79767a0f947e1145f82eb65dfe4360d25f did this for a related requirement in other tests, but I suspect FREEZE is necessary and sufficient in all these tests. Back-patch to v17, where the test first appeared. Reported-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/sv3taq4e6ea4qckimien3nxp3sz4b6cw6sfcy4nhwl52zpur4g@h6i6tohxmizu Backpatch-through: 17 Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/42bb4fb7281ec4881c8a9bac14e1ea7206d0e63d Modified Files -------------- .../expected/syscache-update-pruned.out | 6 ++--- .../expected/syscache-update-pruned_1.out | 6 ++--- .../modules/injection_points/regress_injection.c | 17 +++++++++---- .../specs/syscache-update-pruned.spec | 28 ++++++++++++++++++---- 4 files changed, 41 insertions(+), 16 deletions(-) ^ permalink raw reply [nested|flat] 2+ messages in thread
* pgsql: Fix test races between syscache-update-pruned.spec and autovacuu @ 2025-04-09 14:25 Noah Misch <noah@leadboat.com> 0 siblings, 0 replies; 2+ messages in thread From: Noah Misch @ 2025-04-09 14:25 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix test races between syscache-update-pruned.spec and autovacuum. This spec fails ~3% of my Valgrind runs, and the spec has failed on Valgrind buildfarm member skink at a similar rate. Two problems contributed to that: - A competing buffer pin triggered VACUUM's lazy_scan_noprune() path, causing "tuples missed: 1 dead from 1 pages not removed due to cleanup lock contention". FREEZE fixes that. - The spec ran lazy VACUUM immediately after VACUUM FULL. The spec implicitly assumed lazy VACUUM prunes the one tuple that VACUUM FULL made dead. First wait for old snapshots, making that assumption reliable. This also adds two forms of defense in depth: - Wait for snapshots using shared catalog pruning rules (VISHORIZON_SHARED). This avoids the removable cutoff moving backward when an XID-bearing autoanalyze process runs in another database. That may never happen in this test, but it's cheap insurance. - Use lazy VACUUM option DISABLE_PAGE_SKIPPING. Commit c2dc1a79767a0f947e1145f82eb65dfe4360d25f did this for a related requirement in other tests, but I suspect FREEZE is necessary and sufficient in all these tests. Back-patch to v17, where the test first appeared. Reported-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/sv3taq4e6ea4qckimien3nxp3sz4b6cw6sfcy4nhwl52zpur4g@h6i6tohxmizu Backpatch-through: 17 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/5bbc596391aeaf9042536cc25ce71f1e4fce6db8 Modified Files -------------- .../expected/syscache-update-pruned.out | 6 ++--- .../expected/syscache-update-pruned_1.out | 6 ++--- .../modules/injection_points/regress_injection.c | 17 +++++++++---- .../specs/syscache-update-pruned.spec | 28 ++++++++++++++++++---- 4 files changed, 41 insertions(+), 16 deletions(-) ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2025-04-09 14:25 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2025-04-09 14:25 pgsql: Fix test races between syscache-update-pruned.spec and autovacuu Noah Misch <noah@leadboat.com> 2025-04-09 14:25 pgsql: Fix test races between syscache-update-pruned.spec and autovacuu Noah Misch <noah@leadboat.com>
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