Horton

Re: shared-memory based stats collector

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: michael@paquier.xyz, alvherre@2ndquadrant.com, thomas.munro@gmail.com, tomas.vondra@2ndquadrant.com, a.zakirov@postgrespro.ru, ah@cybertec.at, magnus@hagander.net, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, pgsql-hackers@postgresql.org
Date: 2020-03-13T17:09:00Z
Lists: pgsql-hackers 
Hi,

On 2020-03-13 16:34:50 +0900, Kyotaro Horiguchi wrote:
> Thank you very much!!
> 
> At Thu, 12 Mar 2020 20:13:24 -0700, Andres Freund <andres@anarazel.de> wrote in 
> > Hi,
> > 
> > Thomas, could you look at the first two patches here, and my review
> > questions?
> > 
> > 
> > General comments about this series:
> > - A lot of the review comments feel like I've written them before, a
> >   year or more ago. I feel this patch ought to be in a much better
> >   state. There's a lot of IMO fairly obvious stuff here, and things that
> >   have been mentioned multiple times previously.
> 
> I apologize for all of the obvious stuff or things that have been
> mentioned..  I'll address them.
> 
> > - There's a *lot* of typos in here. I realize being an ESL is hard, but
> >   a lot of these can be found with the simplest spellchecker.  That's
> >   one thing for a patch that just has been hacked up as a POC, but this
> >   is a multi year thread?
> 
> I'll review all changed part again.  I used ispell but I should have
> failed to check much of the changes.
> 
> > - There's some odd formatting. Consider using pgindent more regularly.
> 
> I'll do so.
> 
> > More detailed comments below.
> 
> Thank you very much for the intensive review, I'm going to revise the
> patch according to them.
> 
> > I'm considering rewriting the parts of the patchset that I don't like -
> > but it'll look quite different afterwards.

I take your response to mean that you'd prefer to evolve the patch
largely on your own? I'm mainly asking because I think there's some
chance that we could till get this into v13, but if so we'll have to go
for it now.

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.