Horton

Re: Improve LWLock tranche name visibility across backends

Sami Imseih <samimseih@gmail.com>

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From: Sami Imseih <samimseih@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-07-15T16:52:19Z
Lists: pgsql-hackers 
> Another random thought: I worry that the dshash approach might be quite a
> bit slower, and IIUC we just need to map an integer to a string.  Maybe we
> should just use a DSA for LWLockTrancheNames. IOW we'd leave it as a char**
> but put it in shared memory.

To use DSA just for this purpose, we would need to maintain an array of
dsa_pointers that reference the string(s), right? I am not clear what you
mean by using dsa to put the char**

--
Sami

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().