Question

I have a PC server and an android client; my android client start a socket connection to server.

While I am connected to server, I also receive data from server to android client;

Here is my code:

Socket socket = null;
DataOutputStream out = null;
DataInputStream in = null;
InputStream inputStream = null; 
OutputStream outputStream = null;
...

public void connectToTCP()
        {

            try
            {   
               socket = new Socket(HOST_ADDRESS, PORT);

                socket.setSoTimeout(30000);
                outputStream = socket.getOutputStream();
                out = new DataOutputStream(outputStream);
                inputStream = socket.getInputStream();
                in = new DataInputStream(inputStream);

                Log.e("TCP-", "Connected");

               while (socket.isConnected()){readBytes();}
            } 
            catch (UnknownHostException e) 
            {

               Log.e("Error in tcp connection","Unknown Host");

            }
            catch (IOException e) 
            {

                Log.e("Error in tcp connection", "Couldn't get I/O for the connection");

            }
        }

    public void readBytes() throws IOException
        {   
            if (in.available() > 0)
            {
                byte[] buffer = new byte[in.available()];
                if (buffer.length > 0)
                {
                    if (mListener != null)
                    {
                        int numberOfBytes = in.read(buffer);
                        mListener.tcpConnectionDataReceived(buffer, numberOfBytes);
                    }
                }
            }
        }

but my problem is in performance. I tested the code on the device and I noticed (from task manager) that the app consume a lot of resources (CPU usage is more than 50%) but when I stop reading from socket by deleting this while loop while (socket.isConnected()){readBytes();} CPU usage becomes less than 1%.

Any ideas to solve this?

Answer 1

You readBytes() method will return immediately if no data is available. Since it’s in a tight loop, you’re essentially continuously checking if there is something available, wasting a lot of CPU power.

With the code you show, you would be better off doing a plain blocking read (i.e. remove the available() check altogether, and use a reasonable, fixed-size buffer).