Horton

Re: race condition in pg_class

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Noah Misch <noah@leadboat.com>
Cc: Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>, Smolkin Grigory <smallkeen@gmail.com>
Date: 2024-06-14T00:58:59Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Replace tests of ALTER DATABASE RESET TABLESPACE.

  2. meson: Flush stdout in testwrap

  3. Fix catcache invalidation of a list entry that's being built

  4. Stop reading uninitialized memory in heap_inplace_lock().

  5. Fix use of uninitialized value in previous commit.

  6. Back-patch "Refactor code in tablecmds.c to check and process tablespace moves"

  7. Fix data loss at inplace update after heap_update().

  8. For inplace update durability, make heap_update() callers wait.

  9. Warn if LOCKTAG_TUPLE is held at commit, under debug_assertions.

  10. Don't lose partitioned table reltuples=0 after relhassubclass=f.

  11. Fix new assertion for MERGE view_name ... DO NOTHING.

  12. Remove configuration-dependent output from new inplace-inval test.

  13. AccessExclusiveLock new relations just after assigning the OID.

  14. Cope with inplace update making catcache stale during TOAST fetch.

  15. Expand comments and add an assertion in nodeModifyTable.c.

  16. Improve test coverage for changes to inplace-updated catalogs.

  17. Lock before setting relhassubclass on RELKIND_PARTITIONED_INDEX.

  18. Lock owned sequences during ALTER TABLE SET { LOGGED | UNLOGGED }.

  19. Make TAP todo_start effects the same under Meson and prove_check.

  20. Add an injection_points isolation test suite.

  21. Add wait event type "InjectionPoint", a custom type like "Extension".

  22. Create waitfuncs.c for pg_isolation_test_session_is_blocked().

  23. Rework planning and execution of UPDATE and DELETE.

On Thu, Jun 13, 2024 at 05:35:49PM -0700, Noah Misch wrote:
> I think the attached covers all comments to date.  I gave everything v3, but
> most patches have just a no-conflict rebase vs. v2.  The exceptions are
> inplace031-inj-wait-event (implements the holding from that branch of the
> thread) and inplace050-tests-inj (updated to cooperate with inplace031).  Much
> of inplace031-inj-wait-event is essentially s/Extension/Custom/ for the
> infrastructure common to the two custom wait event types.

Looking at inplace031-inj-wait-event..

The comment at the top of GetWaitEventCustomNames() requires an
update, still mentioning extensions.

GetWaitEventCustomIdentifier() is incorrect, and should return
"InjectionPoint" in the default case of this class name, no?  I would
just pass the classID to GetWaitEventCustomIdentifier().

It is suboptimal to have pg_get_wait_events() do two scans of
WaitEventCustomHashByName.  Wouldn't it be better to do a single scan,
returning a set of (class_name,event_name) fed to the tuplestore of
this SRF?

 uint32
 WaitEventExtensionNew(const char *wait_event_name)
 {
+	return WaitEventCustomNew(PG_WAIT_EXTENSION, wait_event_name);
+}
+
+uint32
+WaitEventInjectionPointNew(const char *wait_event_name)
+{
+	return WaitEventCustomNew(PG_WAIT_INJECTIONPOINT, wait_event_name);
+}

Hmm.  The advantage of two routines is that it is possible to control
the class IDs allowed to use the custom wait events.  Shouldn't the
second routine be documented in xfunc.sgml?

wait_event_names.txt also needs tweaks, in the shape of a new class
name for the new class "InjectionPoint" so as it can be documented for
its default case.  That's a fallback if an event ID cannot be found,
which should not be the case, still that's more correct than showing
"Extension" for all class IDs covered by custom wait events.
--
Michael