From: Alexander Korotkov <akorotkov@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Get rid of WALBufMappingLock
Date: Mon, 17 Feb 2025 02:25:35 +0000
Message-ID: <E1tjqpD-007X6y-9q@gemulon.postgresql.org> (raw)
Get rid of WALBufMappingLock
Allow multiple backends to initialize WAL buffers concurrently. This way
`MemSet((char *) NewPage, 0, XLOG_BLCKSZ);` can run in parallel without
taking a single LWLock in exclusive mode.
The new algorithm works as follows:
* reserve a page for initialization using XLogCtl->InitializeReserved,
* ensure the page is written out,
* once the page is initialized, try to advance XLogCtl->InitializedUpTo and
signal to waiters using XLogCtl->InitializedUpToCondVar condition
variable,
* repeat previous steps until we reserve initialization up to the target
WAL position,
* wait until concurrent initialization finishes using a
XLogCtl->InitializedUpToCondVar.
Now, multiple backends can, in parallel, concurrently reserve pages,
initialize them, and advance XLogCtl->InitializedUpTo to point to the latest
initialized page.
Author: Yura Sokolov <y.sokolov@postgrespro.ru>
Co-authored-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Pavel Borisov <pashkin.elfe@gmail.com>
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/6a2275b8953a4462d44daf001bdd60b3d48f0946
Modified Files
--------------
src/backend/access/transam/xlog.c | 176 +++++++++++++++++-------
src/backend/utils/activity/wait_event_names.txt | 2 +-
src/include/storage/lwlocklist.h | 2 +-
3 files changed, 132 insertions(+), 48 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: akorotkov@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Get rid of WALBufMappingLock
In-Reply-To: <E1tjqpD-007X6y-9q@gemulon.postgresql.org>
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