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help / color / mirror / Atom feedFrom: Bertrand Drouvot <[email protected]>
To: Fujii Masao <[email protected]>
Cc: Sami Imseih <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: [email protected]
Cc: Zsolt Parragi <[email protected]>
Subject: Re: Flush some statistics within running transactions
Date: Mon, 26 Jan 2026 06:59:28 +0000
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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Hi,
On Thu, Jan 22, 2026 at 04:45:31PM +0000, Bertrand Drouvot wrote:
> On Thu, Jan 22, 2026 at 09:12:18PM +0900, Fujii Masao wrote:
> >
> > With this setup, the following messages were logged once per second:
> >
> > LOG: process 72199 still waiting for ShareLock on transaction 771
> > after 63034.119 ms
> > DETAIL: Process holding the lock: 72190. Wait queue: 72199.
> >
>
> Thanks!
>
> I see, the WaitLatch() in ProcSleep() is "woken up" every 1s due to the
> enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT,...) being set unconditionally
> in ProcessInterrupts(). We need to be more restrictive as to when to enable the
> timeout, I'll fix in the next version.
The attached, to apply on top of 0001, fix the issue. However it handles only the
WaitLatch in ProcSleep() case and I start to have concern about the others WaitLatch()
that would/could be "woken up" every 1s.
Using disable_timeout() and enable_timeout_after() in WaitEventSetWait() does not
look like a great answer to this concern, so I wonder if we should use a larger
flush frequency instead (as proposed up-thread), thoughts?
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 063826ae576..7376dd1f316 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -1322,6 +1322,7 @@ ProcSleep(LOCALLOCK *locallock)
bool allow_autovacuum_cancel = true;
bool logged_recovery_conflict = false;
ProcWaitStatus myWaitStatus;
+ bool anytime_timeout_was_active = false;
/* The caller must've armed the on-error cleanup mechanism */
Assert(GetAwaitedLock() == locallock);
@@ -1398,6 +1399,10 @@ ProcSleep(LOCALLOCK *locallock)
standbyWaitStart = GetCurrentTimestamp();
}
+ anytime_timeout_was_active = get_timeout_active(ANYTIME_STATS_UPDATE_TIMEOUT);
+ if (anytime_timeout_was_active)
+ disable_timeout(ANYTIME_STATS_UPDATE_TIMEOUT, false);
+
/*
* If somebody wakes us between LWLockRelease and WaitLatch, the latch
* will not wait. But a set latch does not necessarily mean that the lock
@@ -1661,6 +1666,9 @@ ProcSleep(LOCALLOCK *locallock)
}
} while (myWaitStatus == PROC_WAIT_STATUS_WAITING);
+ if (anytime_timeout_was_active)
+ enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT, PGSTAT_MIN_INTERVAL);
+
/*
* Disable the timers, if they are still running. As in LockErrorCleanup,
* we must preserve the LOCK_TIMEOUT indicator flag: if a lock timeout has
Attachments:
[text/plain] fix_ProcSleep.txt (1.3K, 2-fix_ProcSleep.txt)
download | inline diff:
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 063826ae576..7376dd1f316 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -1322,6 +1322,7 @@ ProcSleep(LOCALLOCK *locallock)
bool allow_autovacuum_cancel = true;
bool logged_recovery_conflict = false;
ProcWaitStatus myWaitStatus;
+ bool anytime_timeout_was_active = false;
/* The caller must've armed the on-error cleanup mechanism */
Assert(GetAwaitedLock() == locallock);
@@ -1398,6 +1399,10 @@ ProcSleep(LOCALLOCK *locallock)
standbyWaitStart = GetCurrentTimestamp();
}
+ anytime_timeout_was_active = get_timeout_active(ANYTIME_STATS_UPDATE_TIMEOUT);
+ if (anytime_timeout_was_active)
+ disable_timeout(ANYTIME_STATS_UPDATE_TIMEOUT, false);
+
/*
* If somebody wakes us between LWLockRelease and WaitLatch, the latch
* will not wait. But a set latch does not necessarily mean that the lock
@@ -1661,6 +1666,9 @@ ProcSleep(LOCALLOCK *locallock)
}
} while (myWaitStatus == PROC_WAIT_STATUS_WAITING);
+ if (anytime_timeout_was_active)
+ enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT, PGSTAT_MIN_INTERVAL);
+
/*
* Disable the timers, if they are still running. As in LockErrorCleanup,
* we must preserve the LOCK_TIMEOUT indicator flag: if a lock timeout has
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Subject: Re: Flush some statistics within running transactions
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