pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Nathan Bossart <nathandbossart@gmail.com>
To: pgsql-hackers@postgresql.org
Cc: michael@paquier.xyz
Subject: remove WaitEventCustomCounterData
Date: Wed, 8 Jul 2026 21:50:33 -0500
Message-ID: <ak8MeTS9QBmz6DKt@nathan> (raw )
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
Attachments:
v1-0001-remove-WaitEventCustomCounterData.patch (text/plain, 3.0K) download
From 6fe5fb011363d1fc96f97412e0665d13216147b6 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
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)
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Message-ID: <ak8MeTS9QBmz6DKt@nathan>
Permalink: ../ak8MeTS9QBmz6DKt@nathan/
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, michael@paquier.xyz
Subject: Re: remove WaitEventCustomCounterData
In-Reply-To: <ak8MeTS9QBmz6DKt@nathan>
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