Horton

Re: AIO v2.5

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Noah Misch <noah@leadboat.com>
Cc: Antonin Houska <ah@cybertec.at>, 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>
Date: 2025-03-26T00:17:17Z
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 aio: Fix reference to outdated name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

Hi,

On 2025-03-25 09:15:43 -0700, Noah Misch wrote:
> On Tue, Mar 25, 2025 at 11:57:58AM -0400, Andres Freund wrote:
> > FWIW, I prototyped this, it's not hard.
> > 
> > But it can't replace the current WARNING with 100% fidelity: If we read 60
> > blocks in a single smgrreadv, we today would would emit 60 WARNINGs.  But we
> > can't encode that many block offset in single PgAioResult, there's not enough
> > space, and enlarging it far enough doesn't seem to make sense either.
> > 
> > 
> > What we *could* do is to emit one WARNING for each bufmgr.c smgrstartreadv(),
> > with that warning saying that there were N zeroed blocks in a read from block
> > N to block Y and a HINT saying that there are more details in the server log.

It should probably be DETAIL, not HINT...


> Sounds fine.

I got that working. To make it readable, it required changing division of
labor between buffer_readv_complete() and buffer_readv_complete_one() a bit,
but I think it's actually easier to understand now.

Still need to beef up the test infrastructure a bit to make the multi-block
cases more easily testable.


Could use some input on the framing of the message/detail. Right now it's:

ERROR:  invalid page in block 8 of relation base/5/16417
DETAIL: Read of 8 blocks, starting at block 7, 1 other pages in the same read are invalid.

But that doesn't seem great. Maybe:

DETAIL: Read of blocks 7..14, 1 other pages in the same read were also invalid.

But that still isn't really a sentence.

Greetings,

Andres Freund