From: Chao Li <li.evan.chao@gmail.com>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: ji xu <thanksgreed@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Fix bug of clearing of waitStart in ProcWakeup()
Date: Wed, 25 Feb 2026 06:03:14 +0800
Message-ID: <2058F900-0706-4B46-A398-54FDABFD29F7@gmail.com> (raw)
In-Reply-To: <CAHGQGwHJGgZS8iiJVUse1QraMXmYzo+5vw4jd-0MQe5h9pyWXg@mail.gmail.com>
References: <537BD852-EC61-4D25-AB55-BE8BE46D07D7@gmail.com>
<CANWi6YNc+qC7O086svzf1jO=udJNA8+aa0gqp2BS7tyKB7dLaA@mail.gmail.com>
<CAHGQGwHJGgZS8iiJVUse1QraMXmYzo+5vw4jd-0MQe5h9pyWXg@mail.gmail.com>
> On Feb 24, 2026, at 23:41, Fujii Masao <masao.fujii@gmail.com> wrote:
>
> On Tue, Feb 24, 2026 at 4:31 PM ji xu <thanksgreed@gmail.com> wrote:
>>
>>
>> Chao Li <li.evan.chao@gmail.com> 于2026年2月24日周二 14:29写道：
>>>
>>> Since this function is clearly operating on the parameter proc, the only statement that touches MyProc looks suspicious. It should reset proc->waitStart, not MyProc->waitStart.
>>>
>>> As written, it will incorrectly clear the caller’s waitStart instead of the awakened backend’s, potentially leaving a stale waitStart value in the target PGPROC.
>
> Thanks for the report!
>
I just realized that I forgot to attach the patch file. Anyway, that’s just a one-line change.
Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/Attachments:v1-0001-Fix-bug-of-clearing-of-waitStart-in-ProcWakeup.patch (application/octet-stream, 1.1K) download
From 5a741a41f675a8cff11cdbb20c819e4853ed1499 Mon Sep 17 00:00:00 2001
From: "Chao Li (Evan)" <lic@highgo.com>
Date: Tue, 24 Feb 2026 14:11:24 +0800
Subject: [PATCH v1] Fix bug of clearing of waitStart in ProcWakeup()
ProcWakeup() incorrectly resets MyProc->waitStart instead of the
waitStart field of the process being awakened.
Fix by resetting proc->waitStart, which corresponds to the PGPROC
being removed from the wait queue.
This looks like oversight of 46d6e5f.
Author: Chao Li <lic@highgo.com>
Reviewed-by:
Discussion: https://postgr.es/m/
---
src/backend/storage/lmgr/proc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.cindex e2f34075d39..771b006b522 100644--- a/src/backend/storage/lmgr/proc.c+++ b/src/backend/storage/lmgr/proc.c@@ -1715,7 +1715,7 @@ ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus)
proc->waitLock = NULL;
proc->waitProcLock = NULL;
proc->waitStatus = waitStatus;
- pg_atomic_write_u64(&MyProc->waitStart, 0);+ pg_atomic_write_u64(&proc->waitStart, 0);
/* And awaken it */
SetLatch(&proc->procLatch);
--
2.50.1 (Apple Git-155)
=
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Cc: li.evan.chao@gmail.com, masao.fujii@gmail.com, thanksgreed@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: Fix bug of clearing of waitStart in ProcWakeup()
In-Reply-To: <2058F900-0706-4B46-A398-54FDABFD29F7@gmail.com>
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