在本地/远程集群上运行java hadoop作业
我正在尝试在本地/远程集群上运行hadoop作业。 将来这项工作将从Web应用程序执行。 我正试图从eclipse执行这段代码：
public class TestHadoop { private final static String host = "localhost"; public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException { run(); } static void run() throws IOException, InterruptedException, ClassNotFoundException { Configuration conf = new Configuration(); // run on other machine/cluster conf.set("fs.default.name", "hdfs://" + host + ":8020"); conf.set("mapred.job.tracker", "hdfs://" + host + ":8021"); Job job = new Job(conf, "Wordcount"); job.setJarByClass(TestHadoop.class); FileInputFormat.addInputPath(job, new Path("/user/hue/jobsub/sample_data/midsummer.txt")); FileOutputFormat.setOutputPath(job, new Path("/tmp/hadoop-out2")); job.setMapperClass(Map.class); job.setReducerClass(Reduce.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); job.waitForCompletion(true); } static class Map extends Mapper { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); @Override public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String line = value.toString(); StringTokenizer tokenizer = new StringTokenizer(line); while (tokenizer.hasMoreTokens()) { word.set(tokenizer.nextToken()); context.write(word, one); } } } static class Reduce extends Reducer { @Override public void reduce(Text key, Iterable values, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } context.write(key, new IntWritable(sum)); } } } 但是我收到以下错误：
2011-09-30 16:32:39,000 WARN org.apache.hadoop.mapred.Child: Error running child java.lang.RuntimeException: java.lang.ClassNotFoundException: org.mmm.hadoop.TestHadoop$Map at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:996) at org.apache.hadoop.mapreduce.JobContext.getMapperClass(JobContext.java:212) at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:602) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:323) at org.apache.hadoop.mapred.Child$4.run(Child.java:270) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1127) at org.apache.hadoop.mapred.Child.main(Child.java:264) Caused by: java.lang.ClassNotFoundException: org.mmm.hadoop.TestHadoop$Map at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:943) at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:994) ... 8 more 16:33:01.209 [LeaseChecker] DEBUG org.apache.hadoop.hdfs.DFSClient - LeaseChecker is interrupted. java.lang.InterruptedException: sleep interrupted at java.lang.Thread.sleep(Native Method) [na:1.7.0] at org.apache.hadoop.hdfs.DFSClient$LeaseChecker.run(DFSClient.java:1167) ~[hadoop-core-0.20.2-cdh3u1.jar:na] at java.lang.Thread.run(Thread.java:722) [na:1.7.0]
我正在使用CDH3和Hue。 作业列表上显示作业，上面运行的子项错误。
您必须在jar中捆绑自定义映射器/缩减器实现。
job.setJarByClass(TestHadoop.class);
然后将查找该jar并将其传输到集群。
我知道我可能为时已晚，但尝试将Map和Reduce宣布为公开。
mapred.job.tracker url应该是http而不是hdfs …
并使Mapper和Reducer公开..
//error conf.set("mapred.job.tracker", "hdfs://" + host + ":8021");