Revert the addition of GetMaxBackends() and related stuff.

This reverts commits 0147fc7, 4567596, aa64f23, and 5ecd018.
There is no longer agreement that introducing this function
was the right way to address the problem. The consensus now
seems to favor trying to make a correct value for MaxBackends
available to mdules executing their _PG_init() functions.

Nathan Bossart

Discussion: http://postgr.es/m/20220323045229.i23skfscdbvrsuxa@jrouhaud

1 files changed, 8 insertions, 6 deletions

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 3535e9e47d2..3dcaf8a4a5d 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1005,8 +1005,10 @@ PostmasterMain(int argc, char *argv[])
 	LocalProcessControlFile(false);
 
 	/*
-	 * Register the apply launcher.  It's probably a good idea to call this
-	 * before any modules had a chance to take the background worker slots.
+	 * Register the apply launcher.  Since it registers a background worker,
+	 * it needs to be called before InitializeMaxBackends(), and it's probably
+	 * a good idea to call it before any modules had chance to take the
+	 * background worker slots.
 	 */
 	ApplyLauncherRegister();
 
@@ -1027,8 +1029,8 @@ PostmasterMain(int argc, char *argv[])
 #endif
 
 	/*
-	 * Now that loadable modules have had their chance to alter any GUCs,
-	 * calculate MaxBackends.
+	 * Now that loadable modules have had their chance to register background
+	 * workers, calculate MaxBackends.
 	 */
 	InitializeMaxBackends();
 
@@ -6142,7 +6144,7 @@ save_backend_variables(BackendParameters *param, Port *port,
 	param->query_id_enabled = query_id_enabled;
 	param->max_safe_fds = max_safe_fds;
 
-	param->MaxBackends = GetMaxBackends();
+	param->MaxBackends = MaxBackends;
 
 #ifdef WIN32
 	param->PostmasterHandle = PostmasterHandle;
@@ -6375,7 +6377,7 @@ restore_backend_variables(BackendParameters *param, Port *port)
 	query_id_enabled = param->query_id_enabled;
 	max_safe_fds = param->max_safe_fds;
 
-	SetMaxBackends(param->MaxBackends);
+	MaxBackends = param->MaxBackends;
 
 #ifdef WIN32
 	PostmasterHandle = param->PostmasterHandle;