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mirror of https://github.com/postgres/postgres.git synced 2026-10-23 13:29:09 +03:00
Heikki Linnakangas 71d1ace33c Don't sleep with vacuum_delay_point() while holding locks
It's a bad idea to sleep while holding locks, because you might block
another process that wants to acquire the same lock.  Furthermore,
it's not safe to call ProcessConfigFile() in a critical section or
while holding locks.  So avoid calling vacuum_delay_point() while
holding locks, and also make vacuum_delay_point() return quickly
without sleeping if it's called while interrupts cannot be processed.

To find the vacuum_delay_point() calls that were made while holding
locks, I added "Assert(INTERRUPTS_CAN_BE_PROCESSED())" in
vacuum_delay_point() and ran the regression tests.  I didn't include
that Assert in this commit, because there might be more places that do
that that are not covered by the regression tests, including
extensions.

In ginInsertCleanup(), there was already another vacuum_delay_point()
call later in the loop, while not holding any locks, so just remove
the other call that was made while holding the lock.

In hashbucketcleanup(), move the vacuum_delay_point() call up the
stack to its caller.  The call in hashbucketcleanup() was not able to
handle interrupts because it held a lock, and because there were no
vacuum_delay_point() or CHECK_FOR_INTERRUPTS() calls in the caller's
loop, the whole hash index vacuuming phase was uninterruptible by
pending shutdown or query cancel.  Now it can be interrupted between
buckets.  Unfortunately, hashbucketcleanup() has to process all the
bucket's pages in one go without pausing; fixing that would require
changing how hashbucketcleanup()'s lock chaining works.

In acquire_sample_rows(), move the vacuum_delay_point() call in the
loop to between pages, to a time where we're not holding the buffer
lock.

In master, also remove a misleading CHECK_FOR_INTERRUPTS() call from
pgstat_write_statsfile().  It was a no-op because we're always holding
a lock on the current dshash partition at that point.  A call that
does nothing is harmless, but it makes you think that the loop is
interruptible when in reality it's not.

Author: Kevin Rocker <me@kevinrocker.com>
Author: Andrey Borodin <amborodin@acm.org>
Author: Mostafa <mostafa.nabil.nafie@gmail.com>
Reported-by: Greg Burd <greg@burd.me>
Reported-by: Sergei Kornilov <sk@zsrv.org>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Neil Chen <carpenter.nail.cz@gmail.com>
Tested-by: Greg Burd <greg@burd.me>
Discussion: https://postgr.es/m/19628-c2b17d358181a1ea@postgresql.org
Discussion: https://postgr.es/m/492c6247-43d3-477b-8981-fb0c56767b38%40app.fastmail.com
Backpatch-through: 14
2026-10-05 13:12:45 +03:00
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PostgreSQL Database Management System

This directory contains the source code distribution of the PostgreSQL database management system.

PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/installation.html.

The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.

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Зеркало официального репозитория PostgreSQL GIT
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