Merge pull request #459 from Shopify/clarify-max-response-size

Update and simplify doc for MaxResponseSize

sarama.go

@@ -40,7 +40,8 @@ var PanicHandler func(interface{})
 var MaxRequestSize int32 = 100 * 1024 * 1024
 
 // MaxResponseSize is the maximum size (in bytes) of any response that Sarama will attempt to parse. If
-// a broker returns a response message larger than this value, Sarama will return a PacketDecodingError. The
-// default of 100 MiB is aligned with Kafka's default `socket.request.max.bytes`, which is the largest
-// request the broker will attempt to process.
+// a broker returns a response message larger than this value, Sarama will return a PacketDecodingError to
+// protect the client from running out of memory. Please note that brokers do not have any natural limit on
+// the size of responses they send. In particular, they can send arbitrarily large fetch responses to consumers
+// (see https://issues.apache.org/jira/browse/KAFKA-2063).
 var MaxResponseSize int32 = 100 * 1024 * 1024