安装Hama之前，应该首先确保系统中已经安装了hadoop，本集群使用的版本为hadoop-2.3.0
一、下载及解压Hama文件
下载地址：http://www.apache.org/dyn/closer.cgi/hama，选用的是目前最新版本：hama0.6.4。解压之后的存放位置自己设定。
二、修改配置文件
- 在hama-env.sh文件中加入JAVA_HOME变量（分布式情况下，设为机器的值）
- 配置hama-site.xml（分布式情况下，所有机器的配置相同）
bsp.master.address为bsp master地址。fs.default.name参数设置成hadoop里namenode的地址。hama.zookeeper.quorum和 hama.zookeeper.property.clientPort两个参数和zookeeper有关，设置成为zookeeper的quorum server即可，单机伪分布式就是本机地址。
4. 配置groomservers文件。hama与hadoop具有相似的主从结构，该文件存放从节点的IP地址，每个IP占一行。（分布式情况下只需要配置BSPMaster所在的机器即可）
5. hama0.6.4自带的hadoop核心包为1.2.0，与集群hadoop2.3.0不一致，需要进行替换，具体是在hadoop的lib文件夹下找到hadoop-core-2.3.0*.jar和hadoop-test-2.3.0*.jar，拷贝到hama的lib目录下，并删除hadoop-core-1.2.0.jar和hadoop-test-1.2.0.jar两个文件。
6. 此时可能会报找不到类的错， 需加入缺失的jar包。（把hadoop开头的jar包和protobuf-java-2.5.0.jar导入到hama/lib下）
三、编写Hama job
在eclipse下新建Java Project，将hama安装时需要的jar包全部导入工程。
官网中计算PI的例子：
package pi; import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hama.HamaConfiguration;
import org.apache.hama.bsp.BSP;
import org.apache.hama.bsp.BSPJob;
import org.apache.hama.bsp.BSPJobClient;
import org.apache.hama.bsp.BSPPeer;
import org.apache.hama.bsp.ClusterStatus;
import org.apache.hama.bsp.FileOutputFormat;
import org.apache.hama.bsp.NullInputFormat;
import org.apache.hama.bsp.TextOutputFormat;
import org.apache.hama.bsp.sync.SyncException; public class PiEstimator {
private static Path TMP_OUTPUT = new Path("/tmp/pi-"
+ System.currentTimeMillis()); public static class MyEstimator
extends
BSP<NullWritable, NullWritable, Text, DoubleWritable, DoubleWritable> {
public static final Log LOG = LogFactory.getLog(MyEstimator.class);
private String masterTask;
private static final int iterations = 100000; @Override
public void bsp(
BSPPeer<NullWritable, NullWritable, Text, DoubleWritable, DoubleWritable> peer)
throws IOException, SyncException, InterruptedException { int in = 0;
for (int i = 0; i < iterations; i++) {
double x = 2.0 * Math.random() - 1.0, y = 2.0 * Math.random() - 1.0;
if ((Math.sqrt(x * x + y * y) < 1.0)) {
in++;
}
} double data = 4.0 * in / iterations; peer.send(masterTask, new DoubleWritable(data));
peer.sync(); if (peer.getPeerName().equals(masterTask)) {
double pi = 0.0;
int numPeers = peer.getNumCurrentMessages();
DoubleWritable received;
while ((received = peer.getCurrentMessage()) != null) {
pi += received.get();
} pi = pi / numPeers;
peer.write(new Text("Estimated value1 of PI is"),
new DoubleWritable(pi));
}
peer.sync(); int in2 = 0;
for (int i = 0; i < iterations; i++) {
double x = 2.0 * Math.random() - 1.0, y = 2.0 * Math.random() - 1.0;
if ((Math.sqrt(x * x + y * y) < 1.0)) {
in2++;
}
} double data2 = 4.0 * in2 / iterations; peer.send(masterTask, new DoubleWritable(data2));
peer.sync(); if (peer.getPeerName().equals(masterTask)) {
double pi2 = 0.0;
int numPeers = peer.getNumCurrentMessages();
DoubleWritable received;
while ((received = peer.getCurrentMessage()) != null) {
pi2 += received.get();
} pi2 = pi2 / numPeers;
peer.write(new Text("Estimated value2 of PI is"),
new DoubleWritable(pi2));
}
peer.sync(); } @Override
public void setup(
BSPPeer<NullWritable, NullWritable, Text, DoubleWritable, DoubleWritable> peer)
throws IOException {
// Choose one as a master this.masterTask = peer.getPeerName(peer.getNumPeers() / 2);
} @Override
public void cleanup(
BSPPeer<NullWritable, NullWritable, Text, DoubleWritable, DoubleWritable> peer)
throws IOException { // if (peer.getPeerName().equals(masterTask)) {
// double pi = 0.0;
// int numPeers = peer.getNumCurrentMessages();
// DoubleWritable received;
// while ((received = peer.getCurrentMessage()) != null) {
// pi += received.get();
// }
//
// pi = pi / numPeers;
// peer.write(new Text("Estimated value of PI is"),
// new DoubleWritable(pi));
// }
}
} static void printOutput(HamaConfiguration conf) throws IOException {
FileSystem fs = FileSystem.get(conf);
FileStatus[] files = fs.listStatus(TMP_OUTPUT);
for (int i = 0; i < files.length; i++) {
if (files[i].getLen() > 0) {
FSDataInputStream in = fs.open(files[i].getPath());
IOUtils.copyBytes(in, System.out, conf, false);
in.close();
break;
}
} fs.delete(TMP_OUTPUT, true);
} public static void main(String[] args) throws InterruptedException,
IOException, ClassNotFoundException {
// BSP job configuration
HamaConfiguration conf = new HamaConfiguration();
BSPJob bsp = new BSPJob(conf, PiEstimator.class);
// Set the job name
bsp.setJobName("Pi Estimation Example");
bsp.setBspClass(MyEstimator.class);
bsp.setInputFormat(NullInputFormat.class);
bsp.setOutputKeyClass(Text.class);
bsp.setOutputValueClass(DoubleWritable.class);
bsp.setOutputFormat(TextOutputFormat.class);
FileOutputFormat.setOutputPath(bsp, TMP_OUTPUT); BSPJobClient jobClient = new BSPJobClient(conf);
ClusterStatus cluster = jobClient.getClusterStatus(true); if (args.length > 0) {
bsp.setNumBspTask(Integer.parseInt(args[0]));
} else {
// Set to maximum
bsp.setNumBspTask(cluster.getMaxTasks());
} long startTime = System.currentTimeMillis(); if (bsp.waitForCompletion(true)) {
printOutput(conf);
System.out.println("Job Finished in "
+ (System.currentTimeMillis() - startTime) / 1000.0
+ " seconds");
}
} }
View PiEstimator
将工程Export成Jar文件，发到集群上运行。运行命令:
$HAMA_HOME/bin/hama jar jarName.jar
输出：
Current supersteps number: 0（）
Current supersteps number: 4（）
The total number of supersteps: 4（总超级步数目）
Counters: 8（一共8个计数器，如下8个。所有计数器列表待完善）
org.apache.hama.bsp.JobInProgress$JobCounter
SUPERSTEPS=4（BSPMaster超级步数目）
LAUNCHED_TASKS=3（共多少个task）
org.apache.hama.bsp.BSPPeerImpl$PeerCounter
SUPERSTEP_SUM=12（总共的超级步数目，task数目*BSPMaster超级步数目）
MESSAGE_BYTES_TRANSFERED=48（传输信息字节数）
TIME_IN_SYNC_MS=657（同步消耗时间）
TOTAL_MESSAGES_SENT=6（发送信息条数）
TOTAL_MESSAGES_RECEIVED=6（接收信息条数）
TASK_OUTPUT_RECORDS=2（任务输出记录数）
PageRank例子：
package pi; import java.io.IOException; import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hama.HamaConfiguration;
import org.apache.hama.bsp.HashPartitioner;
import org.apache.hama.bsp.TextOutputFormat;
import org.apache.hama.graph.AverageAggregator;
import org.apache.hama.graph.Edge;
import org.apache.hama.graph.GraphJob;
import org.apache.hama.graph.Vertex;
import org.apache.hama.graph.VertexInputReader; /**
* Real pagerank with dangling node contribution.
*/
public class PageRank { public static class PageRankVertex extends
Vertex<Text, NullWritable, DoubleWritable> { static double DAMPING_FACTOR = 0.85;
static double MAXIMUM_CONVERGENCE_ERROR = 0.001; @Override
public void setup(HamaConfiguration conf) {
String val = conf.get("hama.pagerank.alpha");
if (val != null) {
DAMPING_FACTOR = Double.parseDouble(val);
}
val = conf.get("hama.graph.max.convergence.error");
if (val != null) {
MAXIMUM_CONVERGENCE_ERROR = Double.parseDouble(val);
}
} @Override
public void compute(Iterable<DoubleWritable> messages)
throws IOException {
// initialize this vertex to 1 / count of global vertices in this
// graph
if (this.getSuperstepCount() == 0) {
this.setValue(new DoubleWritable(1.0 / this.getNumVertices()));
} else if (this.getSuperstepCount() >= 1) {
double sum = 0;
for (DoubleWritable msg : messages) {
sum += msg.get();
}
double alpha = (1.0d - DAMPING_FACTOR) / this.getNumVertices();
this.setValue(new DoubleWritable(alpha + (sum * DAMPING_FACTOR)));
} // if we have not reached our global error yet, then proceed.
DoubleWritable globalError = this.getAggregatedValue(0);
if (globalError != null && this.getSuperstepCount() > 2
&& MAXIMUM_CONVERGENCE_ERROR > globalError.get()) {
voteToHalt();
return;
} // in each superstep we are going to send a new rank to our
// neighbours
sendMessageToNeighbors(new DoubleWritable(this.getValue().get()
/ this.getEdges().size()));
}
} public static GraphJob createJob(String[] args, HamaConfiguration conf)
throws IOException {
GraphJob pageJob = new GraphJob(conf, PageRank.class);
pageJob.setJobName("Pagerank"); pageJob.setVertexClass(PageRankVertex.class);
pageJob.setInputPath(new Path(args[0]));
pageJob.setOutputPath(new Path(args[1])); // set the defaults
pageJob.setMaxIteration(30);
pageJob.set("hama.pagerank.alpha", "0.85");
// reference vertices to itself, because we don't have a dangling node
// contribution here
pageJob.set("hama.graph.self.ref", "true");
pageJob.set("hama.graph.max.convergence.error", "1"); if (args.length == 3) {
pageJob.setNumBspTask(Integer.parseInt(args[2]));
} // error
pageJob.setAggregatorClass(AverageAggregator.class); // Vertex reader
pageJob.setVertexInputReaderClass(PagerankTextReader.class); pageJob.setVertexIDClass(Text.class);
pageJob.setVertexValueClass(DoubleWritable.class);
pageJob.setEdgeValueClass(NullWritable.class); pageJob.setPartitioner(HashPartitioner.class);
pageJob.setOutputFormat(TextOutputFormat.class);
pageJob.setOutputKeyClass(Text.class);
pageJob.setOutputValueClass(DoubleWritable.class);
return pageJob;
} private static void printUsage() {
System.out.println("Usage: <input> <output> [tasks]");
System.exit(-1);
} public static class PagerankTextReader
extends
VertexInputReader<LongWritable, Text, Text, NullWritable, DoubleWritable> { @Override
public boolean parseVertex(LongWritable key, Text value,
Vertex<Text, NullWritable, DoubleWritable> vertex)
throws Exception {
String[] split = value.toString().split("\t");
for (int i = 0; i < split.length; i++) {
if (i == 0) {
vertex.setVertexID(new Text(split[i]));
} else {
vertex.addEdge(new Edge<Text, NullWritable>(new Text(
split[i]), null));
}
}
return true;
} } public static void main(String[] args) throws IOException,
InterruptedException, ClassNotFoundException {
if (args.length < 2)
printUsage(); HamaConfiguration conf = new HamaConfiguration(new Configuration());
GraphJob pageJob = createJob(args, conf); long startTime = System.currentTimeMillis();
if (pageJob.waitForCompletion(true)) {
System.out.println("Job Finished in "
+ (System.currentTimeMillis() - startTime) / 1000.0
+ " seconds");
}
}
}
View PageRank
输出：
