Nginx + mod_push как использовать broadcast?

location /publish/ {
		set $push_channel_id $arg_cid;
		push_store_messages off;
		push_publisher;
	}
	location /listen/ {
		add_header Access-Control-Allow-Origin *;
		push_subscriber_concurrency broadcast;
		set $push_channel_id $arg_cid;
		default_type application/json;
		push_subscriber;
	}