Enable asynchronize dispatcher by default.

src/backend/utils/misc/guc_gp.c

@@ -4010,7 +4010,7 @@ struct config_int ConfigureNamesInt_gp[] =
 		{"gp_connections_per_thread", PGC_BACKEND, GP_ARRAY_TUNING,
 			gettext_noop("Sets the number of client connections handled in each thread."),
 			NULL,
-			GUC_NOT_IN_SAMPLE | GUC_GPDB_ADDOPT
+			GUC_GPDB_ADDOPT
 		},
 		&gp_connections_per_thread,
 		512, 0, INT_MAX, assign_gp_connections_per_thread, show_gp_connections_per_thread

src/backend/utils/misc/postgresql.conf.sample

@@ -541,7 +541,7 @@ gp_interconnect_type=udpifc
 
 # - Worker Process Creation -
 
-gp_connections_per_thread = 64
+gp_connections_per_thread = 0
 gp_segment_connect_timeout = 600s
 
 # - Resource limits -