[FIXED] Data RACE on Unsubscribe when client connection is closed

Resolves #331

server/client.go

@@ -882,10 +882,12 @@ func (c *client) deliverMsg(sub *subscription, mh, msg []byte) {
 		// unsubscribe and drop message on the floor.
 		if sub.nm == sub.max {
 			c.Debugf("Auto-unsubscribe limit of %d reached for sid '%s'\n", sub.max, string(sub.sid))
-			defer client.unsubscribe(sub)
+			// Due to defer, reverse the code order so that execution
+			// is consistent with other cases where we unsubscribe.
 			if shouldForward {
 				defer client.srv.broadcastUnSubscribe(sub)
 			}
+			defer client.unsubscribe(sub)
 		} else if sub.nm > sub.max {
 			c.Debugf("Auto-unsubscribe limit [%d] exceeded\n", sub.max)
 			client.mu.Unlock()

server/route.go

@@ -575,10 +575,12 @@ func (s *Server) broadcastUnSubscribe(sub *subscription) {
 	}
 	rsid := routeSid(sub)
 	maxStr := _EMPTY_
+	sub.client.mu.Lock()
 	// Set max if we have it set and have not tripped auto-unsubscribe
 	if sub.max > 0 && sub.nm < sub.max {
 		maxStr = fmt.Sprintf(" %d", sub.max)
 	}
+	sub.client.mu.Unlock()
 	proto := fmt.Sprintf(unsubProto, rsid, maxStr)
 	s.broadcastInterestToRoutes(proto)
 }