Why Glassfish 4 loses web socket messages?

Question

I try to use web socket for messages (Glassfish 4 implementation). When I use session.getBasicRemote().sendText it works correctly but if I use session.getAsyncRemote().sendText some messages are lost. For example:

for (int i = 0; i < 200; i++) {
    session.getBasicRemote().sendText("{id: " + envelope.id + ", message: \"dddd\"}");
}

But the client receive around 190-195 messages.