Horton

Re: shared-memory based stats collector - v70

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: andres@anarazel.de
Cc: melanieplageman@gmail.com, pryzby@telsasoft.com, thomas.munro@gmail.com, david.g.johnston@gmail.com, pgsql-hackers@lists.postgresql.org
Date: 2022-04-07T01:36:30Z
Lists: pgsql-hackers 
At Wed, 6 Apr 2022 09:04:09 -0700, Andres Freund <andres@anarazel.de> wrote in 
> > +	 * 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.

(Ouch!)

> > 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?

The string prefixes, since they are a limited set of fixed
strings. That being said, I don't think it's better to use an enum
instead, too.  So I don't object to pass the strings here.

> > 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?

For clarity, I don't dislike it so much.  So, I'm fine with the
current name.

I found that you meant a type by the "str".  I thought it as an
instance (I'm not sure I can express my feeling correctly here..) and
the following functions were in my mind.

char *get_namespace/rel/collation/func_name(Oid someoid)
char *pgstat_slru_name(int slru_idx)

Another instance of the same direction is

ForkNumber forkname_to_number(const char *forkName)

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

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.