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Signed-off-by: Henry Robinson <hrobinson@slack-corp.com>

go/vt/grpccommon/options.go

@@ -30,6 +30,8 @@ var (
 	// accept. Larger messages will be rejected.
 	// Note: We're using 16 MiB as default value because that's the default in MySQL
 	maxMessageSize = 16 * 1024 * 1024
+	// These options override maxMessageSize if > 0, allowing us to control the max
+	// size sending independently from receiving.
 	maxMsgRecvSize = 0
 	maxMsgSendSize = 0
 	// enableTracing sets a flag to enable grpc client/server tracing.
@@ -45,8 +47,8 @@ var (
 // command-line arguments.
 func RegisterFlags(fs *pflag.FlagSet) {
 	fs.IntVar(&maxMessageSize, "grpc_max_message_size", maxMessageSize, "Maximum allowed RPC message size. Larger messages will be rejected by gRPC with the error 'exceeding the max size'.")
-	fs.IntVar(&maxMsgSendSize, "grpc_max_message_send_size", maxMsgSendSize, "")
-	fs.IntVar(&maxMsgRecvSize, "grpc_max_message_recv_size", maxMsgRecvSize, "")
+	fs.IntVar(&maxMsgSendSize, "grpc_max_message_send_size", maxMsgSendSize, "Maximum allowed RPC message size when sending. If 0, defaults to grpc_max_message_size.")
+	fs.IntVar(&maxMsgRecvSize, "grpc_max_message_recv_size", maxMsgRecvSize, "Maximum allowed RPC message size when receiving. If 0, defaults to grpc_max_message_size.")
 	fs.BoolVar(&enableTracing, "grpc_enable_tracing", enableTracing, "Enable gRPC tracing.")
 	fs.BoolVar(&enablePrometheus, "grpc_prometheus", enablePrometheus, "Enable gRPC monitoring with Prometheus.")
 }