dont break out of response stream iterator in benchmark client

src/ruby/qps/client.rb

@@ -134,6 +134,7 @@ class BenchmarkClient
     resp = stub.streaming_call(q.each_item)
     start = Time.now
     q.push(req)
+    pushed_sentinal = false
     resp.each do |r|
       @histogram.add((Time.now-start)*1e9)
       if !@done
@@ -141,8 +142,9 @@ class BenchmarkClient
         start = Time.now
         q.push(req)
       else
-        q.push(self)
-        break
+        q.push(self) unless pushed_sentinal
+	# Continue polling on the responses to consume and release resources
+        pushed_sentinal = true
       end
     end
   end