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Revert recent change to RequestNamedLWLockTranche().

author Nathan Bossart <nathan@postgresql.org>

Thu, 4 Sep 2025 20:34:48 +0000 (15:34 -0500)

committer Nathan Bossart <nathan@postgresql.org>

Thu, 4 Sep 2025 20:34:48 +0000 (15:34 -0500)

Commit 38b602b028 modified this function to allocate enough space
for MAX_NAMED_TRANCHES (256) requests, which is likely far more
than most clusters need. This commit reverts that change so that
it first allocates enough space for only 16 requests and resizes
the array when necessary. While at it, remove the check for too
many tranches from this function. We can now rely on
InitializeLWLocks() to do that check via its calls to
LWLockNewTrancheId() for the named tranches.

Reviewed-by: Sami Imseih <samimseih@gmail.com>
Discussion: https://postgr.es/m/aLmzwC2dRbqk14y6%40nathan

src/backend/storage/lmgr/lwlock.c patch | blob | blame | history

diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c

index 258cdebd0f5c992b3fb89c16dbdb9a8f7b30f5ce..fcbac5213a5c045f609a54bd9b062932f799cca4 100644 (file)

--- a/src/backend/storage/lmgr/lwlock.c

+++ b/src/backend/storage/lmgr/lwlock.c

@@ -610,6 +610,7 @@ void

RequestNamedLWLockTranche(const char *tranche_name, int num_lwlocks)

{

NamedLWLockTrancheRequest *request;

+ static int NamedLWLockTrancheRequestsAllocated;

if (!process_shmem_requests_in_progress)

elog(FATAL, "cannot request additional LWLocks outside shmem_request_hook");