Horton

Re: shared-memory based stats collector

Ibrar Ahmed <ibrar.ahmad@gmail.com>

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From: Ibrar Ahmed <ibrar.ahmad@gmail.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Fujii Masao <masao.fujii@oss.nttdata.com>, Georgios Kokolatos <gkokolatos@protonmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-07-19T10:34:56Z
Lists: pgsql-hackers 
On Wed, Apr 7, 2021 at 8:05 AM Kyotaro Horiguchi <horikyota.ntt@gmail.com>
wrote:

> At Tue, 6 Apr 2021 09:32:16 -0700, Andres Freund <andres@anarazel.de>
> wrote in
> > Hi,
> >
> > On 2021-04-05 02:29:14 -0700, Andres Freund wrote:
> ..
> > I'm inclined to push patches
> > [PATCH v60 05/17] pgstat: split bgwriter and checkpointer messages.
> > [PATCH v60 06/17] pgstat: Split out relation stats handling from
> AtEO[Sub]Xact_PgStat() etc.
> > [PATCH v60 09/17] pgstat: xact level cleanups / consolidation.
> > [PATCH v60 10/17] pgstat: Split different types of stats into separate
> files.
> > [PATCH v60 12/17] pgstat: reorder file pgstat.c / pgstat.h contents.
>
> FWIW..
>
> 05 is a straight forward code-rearrange and reasonable to apply.
>
> 06 is same as above and it seems to make things cleaner.
>
> 09 mainly adds ensure_tabtat_xact_level() to remove repeated code
>   blocks a straight-forward way. I wonder if
>   pgstat_xact_stack_level_get() might better be
>   pgstat_get_xact_stack_level(), but I'm fine with the name in the
>   patch.
>
> 10 I found that the kind in "pgstat_kind" meant the placeholder for
>   specific types.  It looks good to separate them into smaller pieces.
>   It is also a simple rearrangement of code.
>
> > pgstat.c is very long, and it's hard to find an order that makes sense
> > and is likely to be maintained over time. Splitting the different
>
>   I deeply agree to "hard to find an order that makes sense".
>
> 12 I'm not sure how it looks after this patch (I failed to apply 09 at
>   my hand.), but it is also a simple rearrangement of code blocks.
>
> > to v14. They're just moving things around, so are fairly low risk. But
> > they're going to be a pain to maintain. And I think 10 and 12 make
> > pgstat.c a lot easier to understand.
>
> I think that pgstat.c doesn't get frequent back-patching.  It seems to
> me that at least 10 looks good.
>
> regards.
>
> --
> Kyotaro Horiguchi
> NTT Open Source Software Center
>
>
>
The patch does not apply, and require rebase,

1 out of 8 hunks FAILED -- saving rejects to file src/include/pgstat.h.rej
patching file src/backend/access/transam/xlog.c
Hunk #1 succeeded at 8758 (offset 34 lines).
patching file src/backend/postmaster/checkpointer.c
Hunk #3 succeeded at 496 with fuzz 1.
Hunk #4 FAILED at 576.
1 out of 6 hunks FAILED -- saving rejects to file
src/backend/postmaster/checkpointer.c.rej
patching file src/backend/postmaster/pgstat.c


I am changing the status to "Waiting on Author".

-- 
Ibrar Ahmed

Commits

  1. Improve comment about dropped entries in pgstat.c

  2. Fix temporary memory leak in system table index scans

  3. pgstat: set timestamps of fixed-numbered stats after a crash.

  4. pgstat: Update docs to match the shared memory stats reality.

  5. pgstat: Hide instability in stats.spec with -DCATCACHE_FORCE_RELEASE.

  6. pgstat: add/extend tests for resetting various kinds of stats.

  7. Add minimal tests for recovery conflict handling.

  8. pgstat: test stats interactions with physical replication.

  9. pgstat: add tests for handling of restarts, including crashes.

  10. pgstat: add tests for transaction behaviour, 2PC, function stats.

  11. pgstat: add pg_stat_have_stats() test helper.

  12. pgstat: add pg_stat_force_next_flush(), use it to simplify tests.

  13. pgstat: move pgstat.c to utils/activity.

  14. pgstat: store statistics in shared memory.

  15. pgstat: remove stats_temp_directory.

  16. pgstat: rename STATS_COLLECTOR GUC group to STATS_CUMULATIVE.

  17. pgstat: revise replication slot API in preparation for shared memory stats.

  18. pgstat: scaffolding for transactional stats creation / drop.

  19. pgstat: introduce PgStat_Kind enum.

  20. pgstat: prepare APIs used by pgstatfuncs for shared memory stats.

  21. pgstat: add pgstat_copy_relation_stats().

  22. pgstat: rename some pgstat_send_* functions to pgstat_report_*.

  23. pgstat: stats collector references in comments.

  24. pgstat: move transactional code into pgstat_xact.c.

  25. dsm: allow use in single user mode.

  26. dshash: revise sequential scan support.

  27. pgstat: remove some superflous comments from pgstat.h.

  28. pgstat: reorder pgstat.[ch] contents.

  29. pgstat: split different types of stats into separate files.

  30. pgstat: introduce pgstat_relation_should_count().

  31. pgstat: separate "xact level" handling out of relation specific functions.

  32. pgstat: rename pgstat_initstats() to pgstat_relation_init().

  33. pgstat: split out WAL handling from pgstat_{initialize,report_stat}.

  34. pgstat: run pgindent on pgstat.c/h.

  35. pgstat: split relation, database handling out of pgstat_report_stat().

  36. Move code around in StartupXLOG().

  37. pgstat: Prepare to use mechanism for truncated rels also for droppped rels.

  38. pgstat: Split out relation stats handling from AtEO[Sub]Xact_PgStat() etc.

  39. pgstat: Schedule per-backend pgstat shutdown via before_shmem_exit().

  40. Schedule ShutdownXLOG() in single user mode using before_shmem_exit().

  41. Make parallel worker shutdown complete entirely via before_shmem_exit().

  42. pgstat: Bring up pgstat in BaseInit() to fix uninitialized use of pgstat by AV.

  43. pgstat: split reporting/fetching of bgwriter and checkpointer stats.

  44. Split backend status and progress related functionality out of pgstat.c.

  45. Split wait event related code from pgstat.[ch] into wait_event.[ch].

  46. Make archiver process an auxiliary process.

  47. Force to send remaining WAL stats to the stats collector at walwriter exit.

  48. Add pg_stat_database counters for sessions and session time

  49. Collect statistics about SLRU caches

  50. Don't run atexit callbacks in quickdie signal handlers.

  51. Create a "fast path" for acquiring weak relation locks.