I am using below client thread for connecting to my NIO server.
class RunnableDemo implements Runnable {
private Thread t;
private String threadName;
InetAddress host = null;
int port = 9090;
RunnableDemo(String name) {
threadName = name;
System.err.println("Creating " + threadName);
}
public void run() {
System.err.println("Running " + threadName);
try {
SocketChannel socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
socketChannel.connect(new InetSocketAddress(host, port));
while (!socketChannel.finishConnect())
;
System.out.println("Thread " + threadName + " Connected");
while (true) {
ByteBuffer buffer = ByteBuffer.allocate(1024);
if (socketChannel.read(buffer) != 0) {
buffer.flip();
byte[] bytes = new byte[buffer.limit()];
buffer.get(bytes);
System.out.println(threadName+ ":" + new String(bytes));
buffer.clear();
}
}
} catch (Exception e) {
System.out.println("Thread " + threadName + " interrupted.");
e.printStackTrace();
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start() {
System.out.println("Starting " + threadName);
try {
host = InetAddress.getByName("127.0.0.1");
if (t == null) {
t = new Thread(this, threadName);
t.start();
}
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
}
This is my server side code. when I running the server side only the CPU is not more than 5% but when I run client for each thread cpu usage will raise about 20-30%
public class EchoServer {
private static final int BUFFER_SIZE = 1024;
private final static int DEFAULT_PORT = 9090;
private long numMessages = 0;
private long loopTime;
private InetAddress hostAddress = null;
private int port;
private Selector selector;
// The buffer into which we'll read data when it's available
private ByteBuffer readBuffer = ByteBuffer.allocate(BUFFER_SIZE);
int timestamp=0;
public EchoServer() throws IOException {
this(DEFAULT_PORT);
}
public EchoServer(int port) throws IOException {
this.port = port;
hostAddress = InetAddress.getByName("127.0.0.1");
selector = initSelector();
loop();
}
private Selector initSelector() throws IOException {
Selector socketSelector = SelectorProvider.provider().openSelector();
ServerSocketChannel serverChannel = ServerSocketChannel.open();
serverChannel.configureBlocking(false);
InetSocketAddress isa = new InetSocketAddress(hostAddress, port);
serverChannel.socket().bind(isa);
serverChannel.register(socketSelector, SelectionKey.OP_ACCEPT);
return socketSelector;
}
private void loop() {
for (;true;) {
try {
selector.select();
Iterator<SelectionKey> selectedKeys = selector.selectedKeys()
.iterator();
while (selectedKeys.hasNext()) {
SelectionKey key = selectedKeys.next();
selectedKeys.remove();
if (!key.isValid()) {
continue;
}
// Check what event is available and deal with it
if (key.isAcceptable()) {
accept(key);
} else if (key.isWritable()) {
write(key);
}
}
Thread.sleep(3000);
timestamp+=3;
} catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
}
}
private void accept(SelectionKey key) throws IOException {
ServerSocketChannel serverSocketChannel = (ServerSocketChannel) key.channel();
SocketChannel socketChannel = serverSocketChannel.accept();
socketChannel.configureBlocking(false);
socketChannel.setOption(StandardSocketOptions.SO_KEEPALIVE, true);
socketChannel.setOption(StandardSocketOptions.TCP_NODELAY, true);
socketChannel.register(selector, SelectionKey.OP_WRITE);
System.out.println("Client is connected");
}
private void write(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
ByteBuffer dummyResponse = ByteBuffer.wrap(("ok:" + String.valueOf(timestamp)) .getBytes("UTF-8"));
socketChannel.write(dummyResponse);
if (dummyResponse.remaining() > 0) {
System.err.print("Filled UP");
}
System.out.println("Message Sent");
// key.interestOps(SelectionKey.OP_READ);
}
}
Every thing works right. Client and server can see each other and communicate. In order to testing how much connection my code can accept I create several instances of above thread and here is the problem.
When I tracking the performance sector of my task panel(windows) by generating each instance of this thread the CPU usage of my PC (I am using a 2.6 core i5 CPU) raise with 30% and by generating 3 thread my cpu usage is about 100% !!!
I am wondering what is the problem with above code that takes 30% of my CPU.
