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: 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: 2025-03-12T23:23:47Z
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 aio: Fix reference to outdated name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

Attachments

Hi,

Attached is v2.7, with the following changes:

- Significantly deduplicated AIO related code bufmgr.c

  Previously the code for temp and shared buffers was duplicated to an
  uncomfortable degree. Now there is a common helper to implements the
  behaviour for both cases.

  The BM_PIN_COUNT_WAITER supporting code was also deduplicated, by
  introducing a helper function.


- Fixed typos / improved phrasing, per Noah's review


- Add comment explaining why retries for EAGAIN for io_uring_enter syscall
  failures don't seem to make sense, improve related error messages slightly


- Added a comment to aio.h explaining that aio_types.h might suffice for
  function declarations and aio_init.h for initialization related code.


- Added and expanded comments for PgAioHandleState, explaining the state
  machine in more detail.


- Updated README to mention the stage callback (instead of the outdated
  "prepare"), plus some other minor cleanups.


- Added a commit rephrasing track_io_timing related docs to talk about waits


- Added FIXME to method_uring.c about the set_max_safe_fds() issue. Depending
  on when/how that is resolved, the relevant commits can be reordered relative
  to the rest.


- Improved localbuf: patches and commit messages, as per Melanie's review


- Added FIXMEs to the bufmgr.c write support (only in later commit, unlikely
  to be realistic for 18) denoting that deadlock risk needs to be
  addressed. We probably need some lwlock.c improvements to make that
  race-free, otherwise I'd just have fixed this.


- Added a comment discussing the placement of the
  TRACE_POSTGRESQL_BUFFER_READ_DONE callback


- removed a few debug ereports() from the StartReadBuffers patch


Unresolved:

- Whether to continue starting new workers in process_pm_child_exit()


- What to name the view (currently pg_aios). I'm inclined to go for
  pg_io_handles right now.


- set_max_safe_fds() related issues for the io_uring backend


Greetings,

Andres Freund