Re: Improve LWLock tranche name visibility across backends

Sami Imseih <samimseih@gmail.com>

From: Sami Imseih <samimseih@gmail.com>

To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

Cc: Rahila Syed <rahilasyed90@gmail.com>, Nathan Bossart <nathandbossart@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2025-07-16T23:17:02Z

Lists: pgsql-hackers

> > Hi,
> >
> > If a dshash table is used to store tranche names and IDs, where would the
> > tranche name for this table
> > be registered?
>
> I guess it could be a new BuiltinTrancheId for this dsa but not sure what
> Nathan
> and Sami have in mind.


Yes, it will be a BuiltinTrancheId for a shared memory that is allocated
during postmaster for tracking tranches. The shared memory will then
only be used by normal backends to register tranches. Any tranche
registered during postmaster is inherited by the backends.

Regards,

Sami

>

Commits

test_dsa: Avoid leaking LWLock tranches.
- c5c74282f2ea 19 (unreleased) landed
Teach DSM registry to ERROR if attaching to an uninitialized entry.
- b26d76f64327 18.2 landed
- ac2800ddc185 17.8 landed
- 1165a933aab1 19 (unreleased) landed
Add a test harness for the LWLock tranche code.
- 16607718c010 19 (unreleased) landed
Revert recent change to RequestNamedLWLockTranche().
- d814d7fc3d52 19 (unreleased) landed
Move dynamically-allocated LWLock tranche names to shared memory.
- 38b602b0289f 19 (unreleased) landed
Prepare DSM registry for upcoming changes to LWLock tranche names.
- 5487058b56e0 19 (unreleased) landed
Add GetNamedDSA() and GetNamedDSHash().
- fe07100e82b0 19 (unreleased) cited