Horton

Re: AIO v2.5

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org, Thomas Munro <thomas.munro@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Robert Haas <robertmhaas@gmail.com>, Jakub Wartak <jakub.wartak@enterprisedb.com>, Jelte Fennema-Nio <postgres@jeltef.nl>, Antonin Houska <ah@cybertec.at>
Date: 2025-04-01T15:11:59Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. aio: Fix assertion, clarify README

  2. aio: Fix reference to outdated name

  3. aio: Fix possible state confusions due to interrupt processing

  4. aio: Improve debug logging around waiting for IOs

  5. aio: Fix crash potential for pg_aios views due to late state update

  6. Increase BAS_BULKREAD based on effective_io_concurrency

  7. localbuf: Add Valgrind buffer access instrumentation

  8. aio: Make AIO more compatible with valgrind

  9. aio: Avoid spurious coverity warning

  10. tests: Fix incompatibility of test_aio with *_FORCE_RELEASE

  11. tests: Cope with WARNINGs during failed CREATE DB on windows

  12. aio: Add errcontext for processing I/Os for another backend

  13. aio: Add README.md explaining higher level design

  14. aio: Minor comment improvements

  15. aio: Add test_aio module

  16. aio: Add pg_aios view

  17. docs: Add acronym and glossary entries for I/O and AIO

  18. Enable IO concurrency on all systems

  19. read_stream: Introduce and use optional batchmode support

  20. docs: Reframe track_io_timing related docs as wait time

  21. bufmgr: Use AIO in StartReadBuffers()

  22. bufmgr: Implement AIO read support

  23. aio: Add WARNING result status

  24. Let caller of PageIsVerified() control ignore_checksum_failure

  25. pgstat: Allow checksum errors to be reported in critical sections

  26. Add errhint_internal()

  27. localbuf: Track pincount in BufferDesc as well

  28. aio, bufmgr: Comment fixes/improvements

  29. Fix mis-attribution of checksum failure stats to the wrong database

  30. aio: Implement support for reads in smgr/md/fd

  31. aio: Add io_method=io_uring

  32. aio: Add liburing dependency

  33. aio: Rename pgaio_io_prep_* to pgaio_io_start_*

  34. aio: Pass result of local callbacks to ->report_return

  35. aio: Be more paranoid about interrupts

  36. Redefine max_files_per_process to control additionally opened files

  37. aio: Change prefix of PgAioResultStatus values to PGAIO_RS_

  38. bufmgr: Improve stats when a buffer is read in concurrently

  39. aio: Add io_method=worker

  40. aio: Infrastructure for io_method=worker

  41. aio: Add core asynchronous I/O infrastructure

  42. aio: Basic subsystem initialization

  43. tests: Expand temp table tests to some pin related matters

  44. localbuf: Introduce FlushLocalBuffer()

  45. localbuf: Introduce TerminateLocalBufferIO()

  46. localbuf: Fix dangerous coding pattern in GetLocalVictimBuffer()

  47. localbuf: Introduce StartLocalBufferIO()

  48. localbuf: Introduce InvalidateLocalBuffer()

  49. Allow lwlocks to be disowned

  50. Make jsonb casts to scalar types translate JSON null to SQL NULL.

  51. bufmgr/smgr: Don't cross segment boundaries in StartReadBuffers()

  52. Use aux process resource owner in walsender

  53. bufmgr: Return early in ScheduleBufferTagForWriteback() if fsync=off

On Mon, Mar 31, 2025 at 08:41:39PM -0400, Andres Freund wrote:
> updated version

All non-write patches (1-7) are ready for commit, though I have some cosmetic
recommendations below.  I've marked the commitfest entry Ready for Committer.

> +		# Check a page validity error in another block, to ensure we report
> +		# the correct block number
> +		$psql_a->query_safe(
> +			qq(
> +SELECT modify_rel_block('tbl_zero', 3, corrupt_header=>true);
> +));
> +		psql_like(
> +			$io_method,
> +			$psql_a,
> +			"$persistency: test zeroing of invalid block 3",
> +			qq(SELECT read_rel_block_ll('tbl_zero', 3, zero_on_error=>true);),
> +			qr/^$/,
> +			qr/^psql:<stdin>:\d+: WARNING:  invalid page in block 3 of relation base\/.*\/.*; zeroing out page$/
> +		);
> +
> +
> +		# Check a page validity error in another block, to ensure we report
> +		# the correct block number

This comment is a copy of the previous test's comment.  While the comment is
not false, consider changing it to:

		# Check one read reporting multiple invalid blocks.

> +		$psql_a->query_safe(
> +			qq(
> +SELECT modify_rel_block('tbl_zero', 2, corrupt_header=>true);
> +SELECT modify_rel_block('tbl_zero', 3, corrupt_header=>true);
> +));
> +		# First test error
> +		psql_like(
> +			$io_method,
> +			$psql_a,
> +			"$persistency: test reading of invalid block 2,3 in larger read",
> +			qq(SELECT read_rel_block_ll('tbl_zero', 1, nblocks=>4, zero_on_error=>false)),
> +			qr/^$/,
> +			qr/^psql:<stdin>:\d+: ERROR:  2 invalid pages among blocks 1..4 of relation base\/.*\/.*\nDETAIL:  Block 2 held first invalid page\.\nHINT:[^\n]+$/
> +		);
> +
> +		# Then test zeroing via ZERO_ON_ERROR flag
> +		psql_like(
> +			$io_method,
> +			$psql_a,
> +			"$persistency: test zeroing of invalid block 2,3 in larger read, ZERO_ON_ERROR",
> +			qq(SELECT read_rel_block_ll('tbl_zero', 1, nblocks=>4, zero_on_error=>true)),
> +			qr/^$/,
> +			qr/^psql:<stdin>:\d+: WARNING:  zeroing out 2 invalid pages among blocks 1..4 of relation base\/.*\/.*\nDETAIL:  Block 2 held first zeroed page\.\nHINT:[^\n]+$/
> +		);
> +
> +		# Then test zeroing vio zero_damaged_pages

s/vio/via/

> +# Verify checksum handling when creating database from an invalid database.
> +# This also serves as a minimal check that cross-database IO is handled
> +# reasonably.

To me, "invalid database" is a term of art from the message "cannot connect to
invalid database".  Hence, I would change "invalid database" to "database w/
invalid block" or similar, here and below.  (Alternatively, just delete "from
an invalid database".  It's clear from the context.)

> +	if (corrupt_checksum)
> +	{
> +		bool		successfully_corrupted = 0;
> +
> +		/*
> +		 * Any single modification of the checksum could just end up being
> +		 * valid again. To be sure
> +		 */

Unfinished sentence.  That said, I'm not following why we'd need this loop.
If this test code were changing the input to the checksum, it's true that an
input bit flip might reach the same pd_checksum.  The test case is changing
pd_checksum, not the input bits.  I don't see how changing pd_checksum could
leave the page still valid.  There's only one valid pd_checksum value for a
given input page.

> +			/*
> +			 * The underlying IO actually completed OK, and thus the "invalid"
> +			 * portion of the IOV actually contains valid data. That can hide
> +			 * a lot of problems, e.g. if we were to wrongly mark a buffer,
> +			 * that wasn't read according to the shortened-read, IO as valid,
> +			 * the contents would look valid and we might miss a bug.

Minimally s/read, IO/read IO,/ but I'd edit a bit further:

			 * a lot of problems, e.g. if we were to wrongly mark-valid a
			 * buffer that wasn't read according to the shortened-read IO, the
			 * contents would look valid and we might miss a bug.

> Subject: [PATCH v2.15 05/18] md: Add comment & assert to buffer-zeroing path
>  in md[start]readv()

> The zero_damaged_pages path is incomplete, as as missing segments are not

s/as as/as/

> For now, put an Assert(false) comments documenting this choice into mdreadv()

s/comments/and comments/

> +				 * For PG 18, we are putting an Assert(false) in into
> +				 * mdreadv() (triggering failures in assertion-enabled builds,

s/in into/in/

> Subject: [PATCH v2.15 06/18] aio: comment polishing

> + * - Partial reads need to be handle by the caller re-issuing IO for the
> + *   unread blocks

s/handle/handled/

> Subject: [PATCH v2.15 07/18] aio: Add errcontext for processing I/Os for
>  another backend