From 5005e5b143bdce05e4d8c9a5598a2114bfe7da2f Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 8 Jun 2020 11:31:28 +1200 Subject: [PATCH] Doc: Update example symptom of systemd misconfiguration. In PostgreSQL 10, we stopped using System V semaphores on Linux systems. Update the example we give of an error message from a misconfigured system to show what people are most likely to see these days. Back-patch to 10, where PREFERRED_SEMAPHORES=UNNAMED_POSIX arrived. Discussion: https://postgr.es/m/CA%2BhUKGLmJUSwybaPQv39rB8ABpqJq84im2UjZvyUY4feYhpWMw%40mail.gmail.com --- doc/src/sgml/runtime.sgml | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index 1b2012d34a..a57c68ce61 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -1120,7 +1120,7 @@ project.max-msg-ids=(priv,4096,deny) If systemd is in use, some care must be taken - that IPC resources (shared memory and semaphores) are not prematurely + that IPC resources (including shared memory) are not prematurely removed by the operating system. This is especially of concern when installing PostgreSQL from source. Users of distribution packages of PostgreSQL are less likely to be affected, as @@ -1137,11 +1137,12 @@ project.max-msg-ids=(priv,4096,deny) - A typical observed effect when this setting is on is that the semaphore - objects used by a PostgreSQL server are removed at apparently random - times, leading to the server crashing with log messages like + A typical observed effect when this setting is on is that shared memory + objects used for parallel query execution are removed at apparently random + times, leading to errors and warnings while attemping to open and remove + them, like -LOG: semctl(1234567890, 0, IPC_RMID, ...) failed: Invalid argument +WARNING: could not remove shared memory segment "/PostgreSQL.1450751626": No such file or directory Different types of IPC objects (shared memory vs. semaphores, System V vs. POSIX) are treated slightly differently -- 2.20.1