Websocket server does not completely send large binary payload

Created by: psl8r

There seems to be an issue in which large binary payloads > ~400KB are not fully sent by a websocket server and therefore not received by the client.

Steps to reproduce:

1. Start a websocket server.

AsyncHttpServer server = new AsyncHttpServer();
server.listen(8000);

server.websocket("/", new AsyncHttpServer.WebSocketRequestCallback() {
    @Override
    public void onConnected(final WebSocket webSocket, AsyncHttpServerRequest request) {

        // TEST: large binary (>400KB) sent from server
        InputStream is = getContext().getResources().openRawResource(R.raw.file1561246251481);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int reads;
        try {
            reads = is.read();
            while (reads != -1) {
                baos.write(reads);
                reads = is.read();
            }

            byte[] payload = baos.toByteArray();

            webSocket.send(payload);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
});

2. Connect from a websocket client and wait to receive

AsyncHttpClient.getDefaultInstance().websocket("http://localhost:8000/", "my-protocol", new WebSocketConnectCallback() {
    @Override
    public void onCompleted(Exception ex, WebSocket webSocket) {
        if (ex != null) {
            ex.printStackTrace();
            return;
        }

        webSocket.setStringCallback(new StringCallback() {
            public void onStringAvailable(String s) {
                System.out.println("I got a string: " + s);
            }
        });
        webSocket.setDataCallback(new DataCallback() {
            public void onDataAvailable(ByteBufferList byteBufferList) {
                System.out.println("I got some bytes!");
                // note that this data has been read
                byteBufferList.recycle();
            }
        });
    }
});

Expected behavior: Receive full binary payload sent by the server.

Actual behavior: Server does not send all the bytes (stepping through using the debugger) and the client DataCallback never fires.

There is actually no issue when sending large binary payloads from a client to the server, only from the server back to the client do I see an issue.

Thanks.