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    <p>I know you want non-blocking NIO, but if you want a performant NIO server I would start with this as a base line if for no other reason than simplicity. Often the simplest is also the fastest.</p> <pre><code>package example.nio; import java.io.Closeable; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class NioEchoServer implements Runnable, Closeable { private final ExecutorService service = Executors.newCachedThreadPool(); private final ServerSocketChannel ssc; private volatile boolean closed = false; public NioEchoServer(int port) throws IOException { ssc = ServerSocketChannel.open(); ssc.socket().setReuseAddress(true); ssc.bind(new InetSocketAddress(port)); service.submit(this); } @Override public void run() { try { while (!closed) { SocketChannel sc = ssc.accept(); service.submit(new EchoHandler(sc)); } } catch (IOException e) { if (!closed) e.printStackTrace(); } finally { closeQuietly(ssc); } } @Override public void close() throws IOException { closed = true; service.shutdownNow(); closeQuietly(ssc); } static void closeQuietly(Closeable closeable) { try { if (closeable != null) closeable.close(); } catch (IOException ignored) { } } public int getPort() { return ssc.socket().getLocalPort(); } static class EchoHandler implements Runnable { private final SocketChannel sc; public EchoHandler(SocketChannel sc) { this.sc = sc; } @Override public void run() { ByteBuffer bb = ByteBuffer.allocateDirect(64 * 1024); try { while (!Thread.interrupted() &amp;&amp; sc.read(bb) &gt; 0) { int len = bb.position(); bb.flip(); while (bb.remaining() &gt; 0) sc.write(bb); // write everything a second time. bb.position(0); bb.limit(len); while (bb.remaining() &gt; 0) sc.write(bb); bb.clear(); } } catch (IOException e) { e.printStackTrace(); } finally { System.out.println("Server disconnected"); closeQuietly(sc); } } } } </code></pre> <hr> <pre><code>package example.nio; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.ByteBuffer; import java.nio.channels.SocketChannel; import java.util.concurrent.atomic.AtomicLong; public class NioEchoClient { public static void main(String... arg) throws IOException, InterruptedException { NioEchoServer nes = new NioEchoServer(0); // use a free port. final SocketChannel sc = SocketChannel.open(new InetSocketAddress("localhost", nes.getPort())); // send data for 2 seconds. long writeCount = 0; final AtomicLong readCount = new AtomicLong(); long start = System.currentTimeMillis(); long end = start + 2000; Thread reader = new Thread(new Runnable() { @Override public void run() { ByteBuffer bb = ByteBuffer.allocateDirect(64 * 1024); bb.clear(); int read; try { while ((read = sc.read(bb)) &gt; 0) { bb.clear(); readCount.addAndGet(read); } } catch (IOException ignored) { } } }); reader.start(); ByteBuffer bb = ByteBuffer.allocateDirect(64 * 1024); while (end &gt; System.currentTimeMillis()) { bb.clear(); int write = sc.write(bb); if (write &lt; 0) throw new AssertionError("Unexpected disconnection?"); writeCount += write; } sc.shutdownOutput(); reader.join(); long time = System.currentTimeMillis() - start; System.out.printf("Wrote: %,d bytes and read: %,d bytes in %,d ms%n", writeCount, readCount.get(), time); sc.close(); nes.close(); } } </code></pre> <p>prints</p> <pre><code>Wrote: 186,318,848 bytes and read: 186,318,848 bytes in 2,001 ms </code></pre> <p>when I write twice as much as I read I get</p> <pre><code>Wrote: 118,161,408 bytes and read: 236,322,816 bytes in 2,002 ms </code></pre>
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    1. PONIO fail when writing more data than reading
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    1. USPeter Lawrey
    1. USPeter Lawrey
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    1. CODo you use my client?
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    2. COI have edited the server to send twice as much as it reads.
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      1. USPeter Lawrey
    3. COWow now I'm even more confused. Albeit this code does produce more stable output values, it still shows a big difference when totalwrite<totalread or the oposite. your code as-is gives me this: Wrote: 1,319,108,608 bytes and read: 1,319,031,008 bytes in 2,001 ms If I write twice (the bb.flip+while twice) then I get this: Wrote: 196,870,144 bytes and read: 393,459,732 bytes in 2,001 ms This is "good" because finally I see the write throughput being double the input, and the values being aligned with my code (input=50-100MB), but the first case is weird, 600MB/s??? I now suspect netcat :(
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      1. USBruno D. Rodrigues
 

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