Horton

Re: shared-memory based stats collector - v70

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: melanieplageman@gmail.com, pryzby@telsasoft.com, thomas.munro@gmail.com, david.g.johnston@gmail.com, pgsql-hackers@lists.postgresql.org
Date: 2022-04-06T16:04:09Z
Lists: pgsql-hackers 
Hi,

On 2022-04-06 18:11:04 +0900, Kyotaro Horiguchi wrote:
> 0004:
> 
> I can see padding_pgstat_send and fun:pgstat_send in valgrind.supp

Those shouldn't be affected by the patch, I think? But I did indeed forget to
remove those in 0010.

> 0006:
> 
> I'm fine with the categorize for now.
> 
> +#define PGSTAT_KIND_LAST PGSTAT_KIND_WAL
> +#define PGSTAT_NUM_KINDS (PGSTAT_KIND_LAST + 1)
> 
> The number of kinds is 10. And PGSTAT_NUM_KINDS is 11?

Yea, it's not great. I think I'll introduce INVALID and rename
PGSTAT_KIND_FIRST to FIRST_VALID.


> +	 * Don't define an INVALID value so switch() statements can warn if some
> +	 * cases aren't covered. But define the first member to 1 so that
> +	 * uninitialized values can be detected more easily.
> 
> FWIW, I like this.

I think there's no switches left now, so it's not actually providing too much.


> 0008:
> 
> +	xact_desc_stats(buf, "", parsed.nstats, parsed.stats);
> +	xact_desc_stats(buf, "commit ", parsed.nstats, parsed.stats);
> +	xact_desc_stats(buf, "abort ", parsed.nabortstats, parsed.abortstats);
> 
> I'm not sure I like this, but I don't object to this..

The string prefixes? Or the entire patch?


> 0010:
> (I didn't look this closer. The comments arised while looking other
> patches.)
> 
> +pgstat_kind_from_str(char *kind_str)
> 
> I don't think I like "str" so much.  Don't we spell it as
> "pgstat_kind_from_name"?

name makes me think of NameData. What do you dislike about str? We seem to use
str in plenty places?


> 0019:
> 
> +my $og_stats = $datadir . '/' . "pg_stat" . '/' . "pgstat.stat";
> 
> It can be "$datadir/pg_stat/pgstat.stat" or $datadir . '/pgstat/pgstat.stat'.
> Isn't it simpler?

Yes, will change.

Greetings,

Andres Freund

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.