Horton

Re: AIO v2.2

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@postgresql.org
Date: 2025-01-07T19:59:58Z
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 aio: Fix reference to outdated name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 Tue, Jan 7, 2025 at 11:11 AM Andres Freund <andres@anarazel.de> wrote:
> The difference between a handle and a reference is useful right now, to have
> some separation between the functions that can be called by anyone (taking a
> PgAioHandleRef) and only by the issuer (PgAioHandle). That might better be
> solved by having a PgAioHandleIssuerRef ref or something.

To me, those names don't convey that. I would perhaps call the thing
that supports issuer-only operations a "PgAio" and the thing other
people can use a "PgAioHandle". Or "PgAioRequest" and "PgAioHandle" or
something like that. With PgAioHandleRef, IMHO you've got two words
that both imply a layer of indirection -- "handle" and "ref" -- which
doesn't seem quite as nice, because then the other thing --
"PgAioHandle" still sort of implies
one layer of indirection and the whole thing seems a bit less clear.

(I say all of this having looked at nothing, so feel free to ignore me
if that doesn't sound coherent.)

> > REAPED feels like a bad name. It sounds like a later stage than COMPLETED,
> > but it's actually vice versa.
>
> What would you call having gotten "completion notifications" from the kernel,
> but not having processed them?

The Linux kernel calls those zombie processes, so we could call it a
ZOMBIE state, but that seems like it might be a bit of inside
baseball. I do agree with Heikki that REAPED sounds later than
COMPLETED, because you reap zombie processes by collecting their exit
status. Maybe you could have AHS_COMPLETE or AHS_IO_COMPLETE for the
state where the I/O is done but there's still completion-related work
to be done, and then the other state could be AHS_DONE or AHS_FINISHED
or AHS_FINAL or AHS_REAPED or something.

-- 
Robert Haas
EDB: http://www.enterprisedb.com