Re: Improve LWLock tranche name visibility across backends

Nathan Bossart <nathandbossart@gmail.com>

From: Nathan Bossart <nathandbossart@gmail.com>

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

Cc: Sami Imseih <samimseih@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Rahila Syed <rahilasyed90@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2025-09-02T14:45:52Z

Lists: pgsql-hackers

On Mon, Sep 01, 2025 at 10:18:46AM +0000, Bertrand Drouvot wrote:
> Changes look good.

Thanks for looking.

> Not directly related, but I think that we can get rid of:
> 
> size = add_size(size, LWLOCK_PADDED_SIZE);
> 
> in LWLockShmemSize() and of:
> 
> ptr += LWLOCK_PADDED_SIZE - ((uintptr_t) ptr) % LWLOCK_PADDED_SIZE;
> 
> in CreateLWLocks(), and just make use of CACHELINEALIGN().

Let's take care of the tranche name stuff first.

-- 
nathan

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