Merge pull request socketio#848 from mbrevoort/redisStoreRaceCondition

Fix Redis Store race condition in manager onOpen unsubscribe callback

lib/manager.js

@@ -343,12 +343,21 @@ Manager.prototype.onConnect = function (id) {
 Manager.prototype.onOpen = function (id) {
   this.open[id] = true;
 
-  // if we were buffering messages for the client, clear them
   if (this.closed[id]) {
     var self = this;
 
     this.store.unsubscribe('dispatch:' + id, function () {
-      delete self.closed[id];
+      var transport = self.transports[id];
+      if (self.closed[id] && self.closed[id].length && transport) {
+
+        // if we have buffered messages that accumulate between calling
+        // onOpen an this async callback, send them if the transport is 
+        // still open, otherwise leave them buffered
+        if (transport.open) {
+          transport.payload(self.closed[id]);
+          self.closed[id] = [];
+        }
+      }
     });
   }