From f08bf94b4f18c7aea9c6e7d3f321c153da7a76d8 Mon Sep 17 00:00:00 2001 From: Ashutosh Bapat Date: Tue, 7 Apr 2026 19:24:15 +0530 Subject: [PATCH v20260407] Unlock ShmemIndexLock before calling init_fn callback CallShmemCallbacksAfterStartup() calls init_fn or attach_fn callbacks while holding ShmemIndexLock. Those callbacks do not require the lock to be held. Before d4885af3d65325c1fcd319e98c634fde9a200443, code initializing the shared structures executed without holding ShmemIndexLock. On the other hand, those callbacks may be performing long running operations like disk access e.g. pgss_shmem_init. Holding a lightweight lock that long should be avoided, if possible. It will cause a delay in loading an extension in all the backends since all attach_fns will be serialized. Author: Ashutosh Bapat --- src/backend/storage/ipc/shmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index 1ebffe5a32a..66b95713020 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -956,6 +956,8 @@ CallShmemCallbacksAfterStartup(const ShmemCallbacks *callbacks) list_free_deep(pending_shmem_requests); pending_shmem_requests = NIL; + LWLockRelease(ShmemIndexLock); + /* Finish by calling the appropriate subsystem-specific callback */ if (found_any) { @@ -968,7 +970,6 @@ CallShmemCallbacksAfterStartup(const ShmemCallbacks *callbacks) callbacks->init_fn(callbacks->opaque_arg); } - LWLockRelease(ShmemIndexLock); shmem_request_state = SRS_DONE; } base-commit: 29e7dbf5e4daa8fafc2b18a1551e7b31c8847340 -- 2.34.1