Each BSP task of the HAMA cluster, will print the LOG string "Hello BSP" in serial order. This example will help you to understand the concepts of BSP computing model.
See below diagram if you don't understand:
public class SerializePrinting { public static class HelloBSP extends BSP { public static final Log LOG = LogFactory.getLog(HelloBSP.class); private Configuration conf; @Override public void bsp(BSPPeer bspPeer) throws IOException, KeeperException, InterruptedException { int num = Integer.parseInt(conf.get("bsp.peers.num")); int i = 0; for(Map.Entry<String, String> e : bspPeer.getAllPeers().entrySet()) { if(bspPeer.getHostName().equals(e.getValue())) { LOG.info("Hello BSP from " + i + " of " + num + ": " + bspPeer.getHostName()); } Thread.sleep(200); bspPeer.sync(); i++; } } @Override public Configuration getConf() { return conf; } @Override public void setConf(Configuration conf) { this.conf = conf; } } public static void main(String[] args) throws InterruptedException, IOException { // BSP job configuration HamaConfiguration conf = new HamaConfiguration(); // Execute locally // conf.set("bsp.master.address", "local"); BSPJob bsp = new BSPJob(conf, SerializePrinting.class); // Set the job name bsp.setJobName("serialize printing"); bsp.setBspClass(HelloBSP.class); BSPJobClient.runJob(bsp); } } |