While trying to understand the extent of our spinlock usage, I noticed that WaitEventCustomCounterData->mutex is unnecessary because the counter is only ever accessed with WaitEventCustomLock held exclusively. So, here's a patch to simplify matters a bit. Thoughts?
-- nathan
>From 6fe5fb011363d1fc96f97412e0665d13216147b6 Mon Sep 17 00:00:00 2001 From: Nathan Bossart <[email protected]> Date: Wed, 8 Jul 2026 21:50:04 -0500 Subject: [PATCH v1 1/1] remove WaitEventCustomCounterData --- src/backend/utils/activity/wait_event.c | 29 ++++++------------------- src/tools/pgindent/typedefs.list | 1 - 2 files changed, 7 insertions(+), 23 deletions(-) diff --git a/src/backend/utils/activity/wait_event.c b/src/backend/utils/activity/wait_event.c index 95635c7f56c..7ee6f99fb50 100644 --- a/src/backend/utils/activity/wait_event.c +++ b/src/backend/utils/activity/wait_event.c @@ -81,14 +81,7 @@ typedef struct WaitEventCustomEntryByName /* dynamic allocation counter for custom wait events */ -typedef struct WaitEventCustomCounterData -{ - int nextId; /* next ID to assign */ - slock_t mutex; /* protects the counter */ -} WaitEventCustomCounterData; - -/* pointer to the shared memory */ -static WaitEventCustomCounterData *WaitEventCustomCounter; +static int *WaitEventCustomCounter; /* first event ID of custom wait events */ #define WAIT_EVENT_CUSTOM_INITIAL_ID 1 @@ -110,8 +103,8 @@ const ShmemCallbacks WaitEventCustomShmemCallbacks = { static void WaitEventCustomShmemRequest(void *arg) { - ShmemRequestStruct(.name = "WaitEventCustomCounterData", - .size = sizeof(WaitEventCustomCounterData), + ShmemRequestStruct(.name = "WaitEventCustomCounter", + .size = sizeof(int), .ptr = (void **) &WaitEventCustomCounter, ); ShmemRequestHash(.name = "WaitEventCustom hash by wait event information", @@ -134,9 +127,8 @@ WaitEventCustomShmemRequest(void *arg) static void WaitEventCustomShmemInit(void *arg) { - /* initialize the allocation counter and its spinlock. */ - WaitEventCustomCounter->nextId = WAIT_EVENT_CUSTOM_INITIAL_ID; - SpinLockInit(&WaitEventCustomCounter->mutex); + /* initialize the allocation counter */ + *WaitEventCustomCounter = WAIT_EVENT_CUSTOM_INITIAL_ID; } /* @@ -221,19 +213,12 @@ WaitEventCustomNew(uint32 classId, const char *wait_event_name) } /* Allocate a new event Id */ - SpinLockAcquire(&WaitEventCustomCounter->mutex); - - if (WaitEventCustomCounter->nextId >= WAIT_EVENT_CUSTOM_HASH_SIZE) - { - SpinLockRelease(&WaitEventCustomCounter->mutex); + if (*WaitEventCustomCounter >= WAIT_EVENT_CUSTOM_HASH_SIZE) ereport(ERROR, errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("too many custom wait events")); - } - - eventId = WaitEventCustomCounter->nextId++; - SpinLockRelease(&WaitEventCustomCounter->mutex); + eventId = (*WaitEventCustomCounter)++; /* Register the new wait event */ wait_event_info = classId | eventId; diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index ffb413ab612..3174e0e4ab8 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -3418,7 +3418,6 @@ WaitEvent WaitEventActivity WaitEventBuffer WaitEventClient -WaitEventCustomCounterData WaitEventCustomEntryByInfo WaitEventCustomEntryByName WaitEventIO -- 2.50.1 (Apple Git-155)
