Horton

Re: Improve LWLock tranche name visibility across backends

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Sami Imseih <samimseih@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, Rahila Syed <rahilasyed90@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-08-18T21:42:09Z
Lists: pgsql-hackers 
On Mon, Aug 18, 2025 at 01:06:42PM -0500, Sami Imseih wrote:
> Attached is v10,

I've been staring at the latest patch for a bit, and I'm a bit concerned
at how much complexity it adds.  I think it's a good idea to keep a local
array of tranche names indexed by tranche ID, but the code for managing the
list of DSA pointers scares me.  I know we were trying to avoid using
dshash earlier, if for no other reason than it's perhaps not the best data
structure for the job, but ISTM we'd eliminate a lot of complexity if we
offloaded the shmem pieces to a dshash table (or some other shmem-based
data structure we have yet to introduce, like a dslist/dsarray).  WDYT?

-- 
nathan

Commits

  1. test_dsa: Avoid leaking LWLock tranches.

  2. Teach DSM registry to ERROR if attaching to an uninitialized entry.

  3. Add a test harness for the LWLock tranche code.

  4. Revert recent change to RequestNamedLWLockTranche().

  5. Move dynamically-allocated LWLock tranche names to shared memory.

  6. Prepare DSM registry for upcoming changes to LWLock tranche names.

  7. Add GetNamedDSA() and GetNamedDSHash().