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help / color / mirror / Atom feedFrom: Alexander Korotkov <[email protected]>
To: [email protected]
Subject: pgsql: Get rid of WALBufMappingLock
Date: Wed, 02 Apr 2025 09:45:59 +0000
Message-ID: <[email protected]> (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 <[email protected]>
Co-authored-by: Alexander Korotkov <[email protected]>
Reviewed-by: Pavel Borisov <[email protected]>
Reviewed-by: Tomas Vondra <[email protected]>
Tested-by: Michael Paquier <[email protected]>
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/bc22dc0e0ddc2dcb6043a732415019cc6b6bf683
Modified Files
--------------
src/backend/access/transam/xlog.c | 234 +++++++++++++++++++-----
src/backend/utils/activity/wait_event_names.txt | 2 +-
src/include/storage/lwlocklist.h | 2 +-
3 files changed, 189 insertions(+), 49 deletions(-)
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