Re: [PATCH v1 0/7] Wait event timing and tracing instrumentation

Hi,

v4 attached. Two changes since v3, no design changes:

* Rebased over current master -- cfbot flagged v3 as needing a rebase
after unrelated drift (typedefs.list and neighbours); no conflicts
in the feature code.

* Dropped the two ereport(WARNING) calls from the recording path, as I
said in my previous message I would do in the next version
regardless. A recorder should not call ereport() from arbitrarily
deep wait sites; the over-cap-LWLock-tranche and unknown-class
overflow conditions stay visible through
pg_stat_wait_event_timing_overflow, which is now their only signal.
Confined to patch 0002.

The API-direction question from my previous message still stands, and
I'd value your read on it whenever you have a moment: whether
whole-session capture behind the runtime level -- with an explicit
escape hatch for call sites where the added cost would be unacceptable
-- is an acceptable shape, or whether explicit per-call-site opt-in is
a prerequisite.

The patches still carry no catversion bump; one is needed at commit
time for 0002, 0003 and 0006.

Regards,
Dmitry Fomin

Dmitry Fomin (7):
wait_event_timing: add --enable-wait-event-timing flag and
wait_event_capture GUC
wait_event_timing: record per-backend wait event statistics (stats
level)
wait_event_timing: expose overflow counters and add reset functions
ci: build one task with --enable-wait-event-timing
wait_event_timing: allocate the per-backend array lazily in DSA
wait_event_timing: add trace level with a per-session ring buffer
wait_event_timing: add query-attribution markers to the trace ring

.github/workflows/pg-ci.yml | 7 +
configure | 32 +
configure.ac | 8 +
doc/src/sgml/config.sgml | 106 +
doc/src/sgml/monitoring.sgml | 783 +++++
meson.build | 1 +
meson_options.txt | 3 +
src/backend/catalog/system_views.sql | 103 +
src/backend/executor/execMain.c | 5 +
src/backend/postmaster/auxprocess.c | 11 +
src/backend/storage/lmgr/proc.c | 5 +
src/backend/tcop/postgres.c | 39 +
src/backend/utils/.gitignore | 1 +
src/backend/utils/Makefile | 9 +-
src/backend/utils/activity/Makefile | 4 +-
src/backend/utils/activity/backend_status.c | 13 +
.../activity/generate-wait_event_types.pl | 179 +
src/backend/utils/activity/meson.build | 1 +
src/backend/utils/activity/wait_event.c | 3 +-
.../utils/activity/wait_event_names.txt | 2 +
.../utils/activity/wait_event_timing.c | 3096 +++++++++++++++++
src/backend/utils/init/postinit.c | 11 +
src/backend/utils/misc/guc_parameters.dat | 29 +
src/backend/utils/misc/guc_tables.c | 1 +
src/backend/utils/misc/postgresql.conf.sample | 5 +
src/include/catalog/pg_proc.dat | 59 +
src/include/pg_config.h.in | 3 +
src/include/storage/lwlocklist.h | 2 +
src/include/storage/subsystemlist.h | 2 +
src/include/utils/.gitignore | 1 +
src/include/utils/guc.h | 1 +
src/include/utils/guc_hooks.h | 3 +
src/include/utils/meson.build | 4 +-
src/include/utils/wait_classes.h | 9 +
src/include/utils/wait_event.h | 49 +
src/include/utils/wait_event_timing.h | 360 ++
src/test/modules/test_misc/meson.build | 1 +
.../t/015_wait_event_trace_seqlock.pl | 122 +
src/test/regress/expected/rules.out | 30 +
.../regress/expected/wait_event_timing.out | 188 +
.../regress/expected/wait_event_timing_1.out | 181 +
src/test/regress/parallel_schedule | 4 +
src/test/regress/sql/wait_event_timing.sql | 113 +
src/tools/pginclude/headerscheck | 2 +
src/tools/pgindent/typedefs.list | 12 +
45 files changed, 5594 insertions(+), 9 deletions(-)
create mode 100644 src/backend/utils/activity/wait_event_timing.c
create mode 100644 src/include/utils/wait_event_timing.h
create mode 100644 src/test/modules/test_misc/t/015_wait_event_trace_seqlock.pl
create mode 100644 src/test/regress/expected/wait_event_timing.out
create mode 100644 src/test/regress/expected/wait_event_timing_1.out
create mode 100644 src/test/regress/sql/wait_event_timing.sql