Horton

Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and more?)

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Magnus Hagander <magnus@hagander.net>, pgsql-hackers@postgresql.org, Lukas Fittl <lukas@fittl.com>, Thomas Munro <thomas.munro@gmail.com>
Date: 2021-12-02T04:06:53Z
Lists: pgsql-hackers 
On Wed, Dec 01, 2021 at 04:59:44PM -0500, Melanie Plageman wrote:
> Thanks for the review!
> 
> On Wed, Nov 24, 2021 at 8:16 PM Justin Pryzby <pryzby@telsasoft.com> wrote:
> > You wrote beentry++ at the start of two loops, but I think that's wrong; it
> > should be at the end, as in the rest of the file (or as a loop increment).
> > BackendStatusArray[0] is actually used (even though its backend has
> > backendId==1, not 0).  "MyBEEntry = &BackendStatusArray[MyBackendId - 1];"
> 
> I've fixed this in v16 which I will attach to the next email in the thread.

I just noticed that since beentry++ is now at the end of the loop, it's being
missed when you "continue":

+               if (beentry->st_procpid == 0)
+                       continue;

Also, I saw that pgindent messed up and added spaces after pointers in function
declarations, due to new typedefs not in typedefs.list:

-pgstat_send_buffers_reset(PgStat_MsgResetsharedcounter *msg)
+pgstat_send_buffers_reset(PgStat_MsgResetsharedcounter * msg)

-static inline void pg_atomic_inc_counter(pg_atomic_uint64 *counter)
+static inline void
+pg_atomic_inc_counter(pg_atomic_uint64 * counter)

-- 
Justin

Commits

  1. Stabilize pg_stat_io writes test

  2. Fix flakey pg_stat_io test

  3. Suppress more compiler warnings in new pgstats code.

  4. Suppress compiler warnings in new pgstats code.

  5. Add tests for pg_stat_io

  6. Create regress_tblspc in test_setup

  7. Add pg_stat_io view, providing more detailed IO statistics

  8. pgstat: Track more detailed relation IO statistics

  9. pgstat: Infrastructure for more detailed IO statistics

  10. doc: Fix some issues in logical replication section

  11. Manual cleanup and pgindent of pgstat and bufmgr related code

  12. Have the planner consider Incremental Sort for DISTINCT

  13. Use actual backend IDs in pg_stat_get_backend_idset() and friends.

  14. Remove redundant call to pgstat_report_wal()

  15. Add BackendType for standalone backends

  16. Initialize backend status reporting during bootstrap.