6d01541960
Commit c758119e5b increased the default number of semaphores required for autovacuum workers from 3 to 16. Unfortunately, some systems have very low default settings for SEMMNS, and this change moved the minimum required for Postgres well beyond that limit (see commit 38da053463 for more details). With this commit, initdb will lower the default value for autovacuum_worker_slots as needed, just like it already does for parameters such as max_connections and shared_buffers. We test for (max_connections / 6) slots, which conveniently has the following properties: * For the initial max_connections default of 100, the default of autovacuum_worker_slots will be 16, which is its initial default value specified in the documentation and in guc_tables.c. * For the lowest possible max_connections default of 25, the default of autovacuum_worker_slots will be 4, which means we only need one additional semaphore for autovacuum workers (as compared to before commit c758119e5b). This leaves some wiggle room for new auxiliary workers, etc. on systems with low SEMMNS, and it ensures that the default number of slots will be greater than or equal to the default value of autovacuum_max_workers (3). Reported-by: Tom Lane Suggested-by: Andres Freund Reviewed-by: Tom Lane Discussion: https://postgr.es/m/1346002.1736198977%40sss.pgh.pa.us
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/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/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/.