1 files changed, 26 insertions, 18 deletions

diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 7b2da2b36f8..7e6a3c17741 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -547,7 +547,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	29
+#define PG_STAT_GET_ACTIVITY_COLS	30
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -686,33 +686,40 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			values[5] = CStringGetTextDatum(clipped_activity);
 			pfree(clipped_activity);
 
-			proc = BackendPidGetProc(beentry->st_procpid);
-			if (proc != NULL)
-			{
-				uint32		raw_wait_event;
+			/* leader_pid */
+			nulls[29] = true;
 
-				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
-				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
-				wait_event = pgstat_get_wait_event(raw_wait_event);
+			proc = BackendPidGetProc(beentry->st_procpid);
 
-			}
-			else if (beentry->st_backendType != B_BACKEND)
+			if (proc == NULL && (beentry->st_backendType != B_BACKEND))
 			{
 				/*
 				 * For an auxiliary process, retrieve process info from
 				 * AuxiliaryProcs stored in shared-memory.
 				 */
 				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+			}
 
-				if (proc != NULL)
-				{
-					uint32		raw_wait_event;
+			/*
+			 * If a PGPROC entry was retrieved, display wait events and lock
+			 * group leader information if any.  To avoid extra overhead, no
+			 * extra lock is being held, so there is no guarantee of
+			 * consistency across multiple rows.
+			 */
+			if (proc != NULL)
+			{
+				uint32		raw_wait_event;
+				PGPROC	   *leader;
 
-					raw_wait_event =
-						UINT32_ACCESS_ONCE(proc->wait_event_info);
-					wait_event_type =
-						pgstat_get_wait_event_type(raw_wait_event);
-					wait_event = pgstat_get_wait_event(raw_wait_event);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+
+				leader = proc->lockGroupLeader;
+				if (leader)
+				{
+					values[29] = Int32GetDatum(leader->pid);
+					nulls[29] = false;
 				}
 			}
 
@@ -908,6 +915,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[26] = true;
 			nulls[27] = true;
 			nulls[28] = true;
+			nulls[29] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);