From 530cfa8eb50ca5a2151dfc50a6a5999ec8aff148 Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Tue, 9 Sep 2025 14:09:36 -0500 Subject: [PATCH] test_slru: Fix LWLock tranche allocation in EXEC_BACKEND builds. Currently, test_slru's shmem_startup_hook unconditionally generates new LWLock tranche IDs. This is fine on non-EXEC_BACKEND builds, where only the postmaster executes this hook, but on EXEC_BACKEND builds, every backend executes it, too. To fix, only generate the tranche IDs in the postmaster process by checking the IsUnderPostmaster variable. This is arguably a bug fix and could be back-patched, but since the damage is limited to some extra unused tranche IDs in a test module, I'm not going to bother. Reported-by: Sami Imseih Reviewed-by: Sami Imseih Discussion: https://postgr.es/m/CAA5RZ0vaAuonaf12CeDddQJu5xKL%2B6xVyS%2B_q1%2BcH%3D33JXV82w%40mail.gmail.com --- src/test/modules/test_slru/test_slru.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/src/test/modules/test_slru/test_slru.c b/src/test/modules/test_slru/test_slru.c index 8c0367eeee4..e963466aef1 100644 --- a/src/test/modules/test_slru/test_slru.c +++ b/src/test/modules/test_slru/test_slru.c @@ -219,8 +219,8 @@ test_slru_shmem_startup(void) */ const bool long_segment_names = true; const char slru_dir_name[] = "pg_test_slru"; - int test_tranche_id; - int test_buffer_tranche_id; + int test_tranche_id = -1; + int test_buffer_tranche_id = -1; if (prev_shmem_startup_hook) prev_shmem_startup_hook(); @@ -231,10 +231,18 @@ test_slru_shmem_startup(void) */ (void) MakePGDirectory(slru_dir_name); - /* initialize the SLRU facility */ - test_tranche_id = LWLockNewTrancheId("test_slru_tranche"); - - test_buffer_tranche_id = LWLockNewTrancheId("test_buffer_tranche"); + /* + * Initialize the SLRU facility. In EXEC_BACKEND builds, the + * shmem_startup_hook is called in the postmaster and in each backend, but + * we only need to generate the LWLock tranches once. Note that these + * tranche ID variables are not used by SimpleLruInit() when + * IsUnderPostmaster is true. + */ + if (!IsUnderPostmaster) + { + test_tranche_id = LWLockNewTrancheId("test_slru_tranche"); + test_buffer_tranche_id = LWLockNewTrancheId("test_buffer_tranche"); + } TestSlruCtl->PagePrecedes = test_slru_page_precedes_logically; SimpleLruInit(TestSlruCtl, "TestSLRU", -- 2.39.5

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