PostgreSQL: Trading Spinlocks for Atomics

Nathan Bossart continued a multi-commit push to replace spinlock-protected fields with atomic variables across the parallel scan and locking code, while separate fixes tightened backup manifest parsing and corrected an error message in the WAL reader.

Duration: PT2M31S

Episode overview

This episode is a short developer briefing from PostgreSQL.

It explains recent repository work in plain language.

  • Show: PostgreSQL
  • Published: 2026-09-05T13:03:36Z
  • Audio duration: PT2M31S

Transcript excerpt

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Good morning. It's September 5th, 2026, and today's PostgreSQL activity centers on one clear engineering theme: getting spinlocks out of hot paths.

Three separate commits from Nathan Bossart convert long-standing spinlock-protected fields to atomic variables. Commit 7344937 handles the start block and block count fields in parallel table scans. Commit 74c7705 does the same for fast-path strong relation lock counts, removing an entire wrapper struct in the…

The second theme is defensive parsing. Fujii Masao's commit 2227afa switches backup manifest LSN parsing over to the standard parse LSN helper. Before this, a malformed or tampered manifest could pass a truncated or malformed LSN through unchecked, potentially causing tools like pg-verify-backup or pg-combine-backup…

Rounding out the batch, Michael Paquier's commit 798bdca fixes an error message in the WAL record decoder that was reporting the wrong length field - a copy-paste oversight from over a decade ago, now backpatched through version 14. And Daniel Gustafsson landed a small documentation cleanup pluralizing "MXID" for…

What to remember: if you're touching parallel scan or lock code, expect atomic operations instead of…

That's…

Nearby episodes from PostgreSQL

  1. Ground Truth for Query Plans and Table Scans
  2. Hardening Edge Cases in Replication and Test Stability
  3. Query Planner Correctness Fixes and Version 19 Cleanup
  4. Integer Overflow Cleanup Across the Tree
  5. Closing the Coverage Gap on Custom Scans
  6. Weekly Recap - Correctness Fixes and Shared Memory Hardening
  7. Dictionary Parsing Gets Hardened
  8. Correctness Fixes for Query Planning and Shared Memory