Upper bound on socket buffer sizes.

CHANGELOG.md

@@ -7,6 +7,9 @@ The format is based on [keep a changelog](http://keepachangelog.com) and this pr
 ### Added
 - Print a log message when all authoritative messages have stopped during graceful shutdown.
 
+### Changed
+- Upper bound on socket buffer sizes. Flush buffer more than once per message if payload size exceeds buffer size.
+
 ## [2.11.1] - 2020-03-29
 ### Changed
 - Update protobuf (1.3.5), websocket (1.4.2), opencensus (0.22.3), atomic (1.6.0), zap (1.14.1) dependencies.

server/socket_ws.go

@@ -29,9 +29,14 @@ import (
 var SocketWsStatsCtx = context.Background()
 
 func NewSocketWsAcceptor(logger *zap.Logger, config Config, sessionRegistry SessionRegistry, matchmaker Matchmaker, tracker Tracker, runtime *Runtime, jsonpbMarshaler *jsonpb.Marshaler, jsonpbUnmarshaler *jsonpb.Unmarshaler, pipeline *Pipeline) func(http.ResponseWriter, *http.Request) {
+	// Select buffer size based on max message size, but cap it to 512KB total (256KB read, 256KB write).
+	bufferSize := 256 * 1024
+	if maxMessageSizeBytes := int(config.GetSocket().MaxMessageSizeBytes); maxMessageSizeBytes < bufferSize {
+		bufferSize = maxMessageSizeBytes
+	}
 	upgrader := &websocket.Upgrader{
-		ReadBufferSize:  int(config.GetSocket().MaxMessageSizeBytes),
-		WriteBufferSize: int(config.GetSocket().MaxMessageSizeBytes),
+		ReadBufferSize:  bufferSize,
+		WriteBufferSize: bufferSize,
 		CheckOrigin:     func(r *http.Request) bool { return true },
 	}