Horton

Re: AIO v2.5

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Ranier Vilela <ranier.vf@gmail.com>
Cc: Noah Misch <noah@leadboat.com>, 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: 2025-04-03T22:30:19Z
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 aio: Fix reference to outdated name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 2025-04-03 16:16:50 -0300, Ranier Vilela wrote:
> Em qui., 3 de abr. de 2025 às 15:35, Andres Freund <andres@anarazel.de>
> escreveu:> > On 2025-04-03 13:46:39 -0300, Ranier Vilela wrote:
> > > Em qua., 2 de abr. de 2025 às 08:58, Andres Freund <andres@anarazel.de>
> > > escreveu:
> > >
> > > > Hi,
> > > >
> > > > I've pushed fixes for 1) and 2) and am working on 3).
> > > >
> > > Coverity has one report about this.
> > >
> > > CID 1596092: (#1 of 1): Uninitialized scalar variable (UNINIT)
> > > 13. uninit_use_in_call: Using uninitialized value result_one. Field
> > > result_one.result is uninitialized when calling pgaio_result_report.
> >
> > Isn't this a rather silly thing to warn about for coverity?
> 
> Personally, I consider every warning to be important.

If the warning is wrong, then it's not helpful. Warning quality really
matters.

Zero-initializing everything *REDUCES* what static analysis and sanitizers can
do. The analyzer/sanitizer can't tell that you just silenced a warning by
zero-initializing something that shouldn't be accessed. If later there is an
access, the zero is probably the wrong value, but the no tool can tell you,
because you did initialize it after all.

> 
> >   The field isn't
> > used in pgaio_result_report().  It can't be a particularly rare thing to
> > have
> > struct fields that aren't always used?
> >
> Always considered a risk, someone may start using it.

That makes it worse! E.g. valgrind won't raise errors about it anymore.

Greetings,

Andres Freund