Horton

Re: shared-memory based stats collector

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: alvherre@2ndquadrant.com
Cc: andres@anarazel.de, michael@paquier.xyz, thomas.munro@gmail.com, tomas.vondra@2ndquadrant.com, ah@cybertec.at, magnus@hagander.net, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, pgsql-hackers@postgresql.org
Date: 2020-04-03T08:31:17Z
Lists: pgsql-hackers

Attachments

Conflicted with the commit 28cac71bd3 - SLRU stats.

Rebased and fixed some issues.

At Wed, 01 Apr 2020 17:37:23 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> > Conflicted with 616ae3d2b0, so rebased.
> 
> I made some cleanup. (v30)
> 
> - Added comments for members of dshash_seq_scans.
> - Some style fix and comment fix of dshash.
> 
> - Cleaned up more usage of the word "stat(istics) collector" in comments,
> - Changed the GUC attribute STATS_COLLECTOR to STATS_ACTIVITY
> - Removed duplicate setup of MyBackendType and ps display in PgArchiverMain
> - Removed B_STATS_COLLECTOR from BackendType and removed related code.
> - Corrected the comment of PgArchiverMain, which mentioned "argv/argc".

I made further cleanups.

- Removed wrongly added BACKEND_TYPE_ARCHIVER.

- Moved archiver latch from XLogCtlData to ProcGlobal.

- Removed XLogArchiverStart/End/Wakeup from xlog.h, where anyway was
  not the proper place.

- pgarch_MainLoop start the loop with wakened = true when both
  notified or timed out. Otherwise time_to_stop is set and exits from
  the loop immediately. So the variable wakened is actually
  useless. Removed it.

- A PoC (or a rush work) of refactoring of SLRU stats.

  I tried to combine it into the global stats hash, but the SLRU
  report functions are called within critical sections so memory
  allocation fails. The current pgstat module removes the local entry
  at successful flushing out to shared stats, so allocation at the
  first report is inevitable.  In the attched version it is handled
  the same way with global stats.  I continue seeking a way to
  combining it to the global stats hash.

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.