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: 2025-04-02T00:13:24Z
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 aio: Fix reference to outdated name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, Apr 01, 2025 at 06:25:28PM -0400, Andres Freund wrote:
> On 2025-04-01 17:47:51 -0400, Andres Freund wrote:
> > 3) Some subtests fail if RELCACHE_FORCE_RELEASE and CATCACHE_FORCE_RELEASE are defined:
> > 
> > https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=prion&dt=2025-04-01%2019%3A23%3A07
> > 
> > # +++ tap check in src/test/modules/test_aio +++
> > 
> > #   Failed test 'worker: batch_start() leak & cleanup in implicit xact: expected stderr'
> > #   at t/001_aio.pl line 318.
> > #                   'psql:<stdin>:4: ERROR:  starting batch while batch already in progress'
> > #     doesn't match '(?^:open AIO batch at end)'
> > 
> > 
> > The problem is basically that the test intentionally forgets to exit batchmode
> > - normally that would trigger an error at the end of the transaction, which
> > the test verifies.  However, with RELCACHE_FORCE_RELEASE and
> > CATCACHE_FORCE_RELEASE defined, we get other code entering batchmode and
> > erroring out because batchmode isn't allowed to be entered recursively.

> > I don't really have a good idea how to deal with that yet.
> 
> Hm. Making the query something like
> 
> SELECT * FROM (VALUES (NULL), (batch_start()));
> 
> avoids the wrong output, because the type lookup happens for the first row
> already. But that's pretty magical and probably fragile.

Hmm.  Some options:

a. VALUES() trick above.  For test code, it's hard to argue with something
   that seems to solve it in practice.

b. Encapsulate the test in a PROCEDURE, so perhaps less happens between the
   batch_start() and the procedure-managed COMMIT.  Maybe less fragile than
   (a), maybe more fragile.

c. Move RELCACHE_FORCE_RELEASE and CATCACHE_FORCE_RELEASE to be
   GUC-controlled, like how CLOBBER_CACHE_ALWAYS changed into the
   debug_discard_caches GUC.  Then disable them for relevant parts of
   test_aio.  This feels best long-term, but it's bigger.  I also wanted this
   in syscache-update-pruned.spec[1].

d. Have test_aio deduce whether these are set, probably by observing memory
   contexts or DEBUG messages.  Maybe have every postmaster startup print a
   DEBUG message about these settings being enabled.  Skip relevant parts of
   test_aio.  This sounds messy.

Each of those feels defensible to me.  I'd probably do (a) or (b) to start.


[1] For that spec, an alternative expected output sufficed.  Incidentally,
I'll soon fix that spec flaking on valgrind/skink.