Use defer_stop in sleep example for graceful shutdown.

examples/sleep/config.ru

@@ -4,21 +4,17 @@ require 'async'
 run do
 	body = Async::HTTP::Body::Writable.new
 
-	Async do
-		30.times do
-			body.write "(#{Time.now}) Hello World #{Process.pid}\n"
-			sleep 1
+	Async do |task|
+		task.defer_stop do
+			30.times do
+				body.write "(#{Time.now}) Hello World #{Process.pid}\n"
+				sleep 1
+			end
 		end
 	ensure
+		Console.info(self, "Closing body...")
 		body.close
 	end
 
 	[200, {}, body]
 end
-
-# Run the server:
-# > falcon serve --count 1 --bind http://localhost:9292
-
-# Measure the concurrency:
-# > benchmark-http concurrency -t 1.2 -c 0.9 http://localhost:9292
-