Remove pg_wait_for_backend_termination().

It was unable to wait on a backend that had already left the procarray.
Users tolerant of that limitation can poll pg_stat_activity.  Other
users can employ the "timeout" argument of pg_terminate_backend().

Reviewed by Bharath Rupireddy.

Discussion: https://postgr.es/m/20210605013236.GA208701@rfd.leadboat.com

4 files changed, 1 insertions, 46 deletions

diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index a4373b176c6..a416e94d371 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -397,11 +397,6 @@ CREATE OR REPLACE FUNCTION
   RETURNS boolean STRICT VOLATILE LANGUAGE INTERNAL AS 'pg_terminate_backend'
   PARALLEL SAFE;
 
-CREATE OR REPLACE FUNCTION
-  pg_wait_for_backend_termination(pid integer, timeout int8 DEFAULT 5000)
-  RETURNS boolean STRICT VOLATILE LANGUAGE INTERNAL AS 'pg_wait_for_backend_termination'
-  PARALLEL SAFE;
-
 -- legacy definition for compatibility with 9.3
 CREATE OR REPLACE FUNCTION
   json_populate_record(base anyelement, from_json json, use_json_as_text boolean DEFAULT false)
diff --git a/src/backend/storage/ipc/signalfuncs.c b/src/backend/storage/ipc/signalfuncs.c
index 0a111ad6daa..43386c5bb32 100644
--- a/src/backend/storage/ipc/signalfuncs.c
+++ b/src/backend/storage/ipc/signalfuncs.c
@@ -231,42 +231,6 @@ pg_terminate_backend(PG_FUNCTION_ARGS)
 }
 
 /*
- * Wait for a backend process with the given PID to exit or until the given
- * timeout milliseconds occurs. Returns true if the backend has exited. On
- * timeout a warning is emitted and false is returned.
- *
- * We allow any user to call this function, consistent with any user being
- * able to view the pid of the process in pg_stat_activity etc.
- */
-Datum
-pg_wait_for_backend_termination(PG_FUNCTION_ARGS)
-{
-	int			pid;
-	int64		timeout;
-	PGPROC	   *proc = NULL;
-
-	pid = PG_GETARG_INT32(0);
-	timeout = PG_GETARG_INT64(1);
-
-	if (timeout <= 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
-				 errmsg("\"timeout\" must not be negative or zero")));
-
-	proc = BackendPidGetProc(pid);
-
-	if (proc == NULL)
-	{
-		ereport(WARNING,
-				(errmsg("PID %d is not a PostgreSQL server process", pid)));
-
-		PG_RETURN_BOOL(false);
-	}
-
-	PG_RETURN_BOOL(pg_wait_until_termination(pid, timeout));
-}
-
-/*
  * Signal to reload the database configuration
  *
  * Permission checking for this function is managed through the normal
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index d5dada949c3..1b23c7c253b 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202106101
+#define CATALOG_VERSION_NO	202106151
 
 #endif
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 83eea85cf64..fde251fa4f3 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6190,10 +6190,6 @@
   proname => 'pg_terminate_backend', provolatile => 'v', prorettype => 'bool',
   proargtypes => 'int4 int8', proargnames => '{pid,timeout}',
   prosrc => 'pg_terminate_backend' },
-{ oid => '2137', descr => 'wait for a backend process exit or timeout occurs',
-  proname => 'pg_wait_for_backend_termination', provolatile => 'v',
-  prorettype => 'bool', proargtypes => 'int4 int8',
-  proargnames => '{pid,timeout}', prosrc => 'pg_wait_for_backend_termination' },
 { oid => '2172', descr => 'prepare for taking an online backup',
   proname => 'pg_start_backup', provolatile => 'v', proparallel => 'r',
   prorettype => 'pg_lsn', proargtypes => 'text bool bool',