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: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-08-06T04:24:04Z
Lists: pgsql-hackers

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> I'll fix this in the next rev.

v5 fixes the above 2 issues found above.

For the issue that was throwing ".... segment that has been freed",
indeed we should be freeing LWLockTrancheNames.shmem->list_ptr,
list_ptr is a dsa_pointer that stores an array of dsa_pointers, which
then made me realize that I was not freeing the actual dsa_pointers
holding the tranche names. I fixed that as well.

I also made some improvements to the code that copies the old
list to the new list and fixed the lookup in
GetLWTrancheName.

--
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().