mirror of
https://github.com/postgres/postgres.git
synced 2025-07-15 19:21:59 +03:00
6d01541960
Commitc758119e5bincreased 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 commit38da053463for 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 commitc758119e5b). 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