v6-0003-Reflect-the-value-of-max_safe_fds-in-max_files_pe.patch

From faf1c3b550215a6dc831d5fc9ee4e5c2ec5604a4 Mon Sep 17 00:00:00 2001
From: Jelte Fennema-Nio <github-tech@jeltef.nl>
Date: Wed, 12 Feb 2025 01:08:07 +0100
Subject: [PATCH v6 3/3] Reflect the value of max_safe_fds in
 max_files_per_process

It is currently hard to figure out if max_safe_fds is significantly
lower than max_files_per_process. This starts reflecting the value of
max_safe_fds in max_files_per_process after our limit detection. We
still want to have two separate variables because for the bootstrap or
standalone-backend cases their values differ on purpose.
---
 src/backend/storage/file/fd.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index fc60e7ebeb9..f0643838857 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -1198,6 +1198,7 @@ set_max_safe_fds(void)
 {
 	int			usable_fds;
 	int			already_open;
+	char	   *max_safe_fds_string;
 
 	/*----------
 	 * We want to set max_safe_fds to
@@ -1212,6 +1213,12 @@ set_max_safe_fds(void)
 
 	max_safe_fds = Min(usable_fds - NUM_RESERVED_FDS, max_files_per_process);
 
+	/* Update GUC variable to allow users to see the result */
+	max_safe_fds_string = psprintf("%d", max_safe_fds);
+	SetConfigOption("max_files_per_process", max_safe_fds_string,
+					PGC_POSTMASTER, PGC_S_OVERRIDE);
+	pfree(max_safe_fds_string);
+
 	/*
 	 * Make sure we still have enough to get by.
 	 */
-- 
2.43.0