From e4f8da7d5fbae73c0852f621e2f2d690fefe3d58 Mon Sep 17 00:00:00 2001
From: chimurai <stevenchim@gmail.com>
Date: Mon, 26 Sep 2016 22:27:34 +0200
Subject: [PATCH] bug(websocket): fix memory leak when option 'ws:true' is
 used.

---
 lib/index.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/index.js b/lib/index.js
index 8ac7d8bb..9c40ff60 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -13,6 +13,7 @@ module.exports = HttpProxyMiddleware;
 function HttpProxyMiddleware(context, opts) {
     // https://github.com/chimurai/http-proxy-middleware/issues/57
     var wsUpgradeDebounced  = _.debounce(handleUpgrade);
+    var wsInitialized       = false;
     var config              = configFactory.createConfig(context, opts);
     var proxyOptions        = config.options;
 
@@ -43,15 +44,24 @@ function HttpProxyMiddleware(context, opts) {
         }
 
         if (proxyOptions.ws === true) {
+            // use initial request to access the server object to subscribe to http upgrade event
             catchUpgradeRequest(req.connection.server);
         }
     }
 
     function catchUpgradeRequest(server) {
-        server.on('upgrade', wsUpgradeDebounced);
+        // subscribe once; don't subscribe on every request...
+        // https://github.com/chimurai/http-proxy-middleware/issues/113
+        if (!wsInitialized) {
+            server.on('upgrade', wsUpgradeDebounced);
+            wsInitialized = true;
+        }
     }
 
     function handleUpgrade(req, socket, head) {
+        // set to initialized when used externally
+        wsInitialized = true;
+
         if (shouldProxy(config.context, req)) {
             var activeProxyOptions = prepareProxyRequest(req);
             proxy.ws(req, socket, head, activeProxyOptions);