public inbox for [email protected]
help / color / mirror / Atom feedFrom: Michael Paquier <[email protected]>
To: [email protected]
Subject: pgsql: Fix race leading to incorrect conflict cause in InvalidatePossib
Date: Tue, 20 Feb 2024 04:44:21 +0000
Message-ID: <[email protected]> (raw)
Fix race leading to incorrect conflict cause in InvalidatePossiblyObsoleteSlot()
The invalidation of an active slot is done in two steps:
- Termination of the backend holding it, if any.
- Report that the slot is obsolete, with a conflict cause depending on
the slot's data.
This can be racy because between these two steps the slot mutex would be
released while doing system calls, which means that the effective_xmin
and effective_catalog_xmin could advance during that time, detecting a
conflict cause different than the one originally wanted before the
process owning a slot is terminated.
Holding the mutex longer is not an option, so this commit changes the
code to record the LSNs stored in the slot during the termination of the
process owning the slot.
Bonus thanks to Alexander Lakhin for the various tests and the analysis.
Author: Bertrand Drouvot
Reviewed-by: Michael Paquier, Bharath Rupireddy
Discussion: https://postgr.es/m/[email protected]
Backpatch-through: 16
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/818fefd8fd4412d45eb542155cb2833a2b864acc
Modified Files
--------------
src/backend/replication/slot.c | 39 +++++++++++++++++++++++++++++++++------
1 file changed, 33 insertions(+), 6 deletions(-)
view thread (4+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: pgsql: Fix race leading to incorrect conflict cause in InvalidatePossib
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox