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POSpeed up my Java tcp transfer!
 

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  1. POSpeed up my Java tcp transfer!
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    <p>I need to speed up transfers across my gigabit ethernet connection. Right now, I'm doing something almost exactly like this, but I'm only seeing about 40% of that when I run this code below.</p> <p>I also ran this script on all of my (Mac Pro) machines before testing</p> <pre><code>#!/bin/bash sudo sysctl -w net.inet.tcp.win_scale_factor=8 sudo sysctl -w kern.ipc.maxsockbuf=16777216 sudo sysctl -w net.inet.tcp.sendspace=8388608 sudo sysctl -w net.inet.tcp.recvspace=8388608 </code></pre> <p>The actual code follows:</p> <pre><code>import java.io.*; import java.nio.*; import java.net.*; public class BandwidthTester { private static final int OUT_BUF = (1 &lt;&lt; 17), IN_BUF = (1 &lt;&lt; 17), SEND_BUF = (1 &lt;&lt; 22), RECV_BUF = (1 &lt;&lt; 22); public static void main(String[] args) { try { // server if (args.length == 0) { ServerSocket sock = new ServerSocket(); sock.bind(new InetSocketAddress(41887)); // wait for connection Socket s = sock.accept(); s.setSendBufferSize(SEND_BUF); System.out.println("Buffers: " + s.getSendBufferSize() + " and " + s.getReceiveBufferSize()); sock.close(); BufferedOutputStream bOut = new BufferedOutputStream(s.getOutputStream(), OUT_BUF); // send lots of data sendLotsOfData(bOut); } else if (args.length == 2) { String host = args[0]; int port = Integer.parseInt(args[1]); System.out.println("Connecting to " + args[0] + ":" + args[1]); Socket sock = new Socket(); sock.setReceiveBufferSize(RECV_BUF); sock.connect(new InetSocketAddress(host, port)); System.out.println("Buffers: " + sock.getSendBufferSize() + " and " + sock.getReceiveBufferSize()); BufferedInputStream bIn = new BufferedInputStream(sock.getInputStream(), IN_BUF); getLotsOfData(bIn); } } catch (Exception e) { e.printStackTrace(); } } public static void getLotsOfData(InputStream in) { System.out.println("Getting data..."); try { long start = System.currentTimeMillis(); ByteBuffer intConv = ByteBuffer.allocate(4); in.read(intConv.array()); int len = intConv.getInt(0); for (int i=0; i &lt; len; i++) { in.read(intConv.array()); int val = intConv.getInt(0); } long end = System.currentTimeMillis(); double elapsed = ((double)(end - start)) / (1000.0); System.out.println("Read in " + elapsed + " seconds: " + ( (4.0*8.0*len/elapsed) + " bits per second")); } catch (Exception e) { e.printStackTrace(); } } public static void sendLotsOfData(OutputStream out) { System.out.println("Sending data..."); try { long start = System.currentTimeMillis(); int len = (1 &lt;&lt; 29); ByteBuffer intConv = ByteBuffer.allocate(4); intConv.putInt(0, len); out.write(intConv.array()); for (int i=0; i &lt; len; i++) { intConv.putInt(0, i); out.write(intConv.array()); } out.flush(); long end = System.currentTimeMillis(); double elapsed = ((double)(end - start)) / (1000.0); System.out.println("Sent in " + elapsed + " seconds: " + ( (4.0*8.0*len/elapsed) + " bits per second")); } catch (Exception e) { e.printStackTrace(); } } } </code></pre> <p>Any suggestions? It's taking about 42 seconds to send all of that data, but even a 10% improvement here would have a dramatic impact on my program.</p>
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