Horton

Re: Weird test mixup

Noah Misch <noah@leadboat.com>

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From: Noah Misch <noah@leadboat.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2024-05-06T21:23:24Z
Lists: pgsql-hackers

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On Mon, May 06, 2024 at 10:03:37AM +0900, Michael Paquier wrote:
> On Thu, May 02, 2024 at 12:35:55PM -0700, Noah Misch wrote:
> > I should have given a simpler example:
> > 
> > s1: local-attach to POINT
> > s2: enter InjectionPointRun(POINT), yield CPU just before injection_callback()
> > s1: exit
> > s2: wake up and run POINT as though it had been non-local

Here's how I've patched it locally.  It does avoid changing the backend-side,
which has some attraction.  Shall I just push this?

> Hmm.  Even if you were to emulate that in a controlled manner, you
> would need a second injection point that does a wait in s2, which is
> something that would happen before injection_callback() and before
> scanning the local entry.  This relies on the fact that we're holding
> CPU in s2 between the backend shmem hash table lookup and the callback
> being called.

Right.  We would need "second-level injection points" to write a test for that
race in the injection point system.

Commits

  1. injection_points: Store runtime conditions in private area

  2. Introduce private data area for injection points

  3. injection_points: Fix incorrect spinlock acquisition

  4. Make GIN tests using injection points concurrent-safe

  5. injection_points: Fix race condition with local injection point tests

  6. injection_points: Introduce runtime conditions

  7. Make GIN test using injection points repeatable

  8. Fix backstop in gin test if injection point is not reached

  9. Try to unbreak injection-fault tests in the buildfarm

  10. Disable tests using injection points in installcheck