The MultipleOutput instance in Hadoop uses the

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Expected results after processing:

MyMapper.java

Package com.xr.text;import java.io.IOException;import org.apache.hadoop.io.LongWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Mapper;public class MyMapper extends Mapper {protected void map (LongWritable key, Text value,Context context) throws IOException, InterruptedException {String [] split = value.toString. Split (";") Context.write (new Text (split [0]), new Text (split [1]));}}

MyReducer.java

Package com.xr.text;import java.io.IOException;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.output.MultipleOutputs;public class MyReducer extends Reducer {private MultipleOutputs mos; / * start before set MultipleOutputs * / protected void setup (Context context) throws IOException, InterruptedException {mos = new MultipleOutputs (context);} protected void reduce (Text K1, Iterable value,Context context) throws IOException, InterruptedException {String key = k1.toString () For (Text t: value) {if ("China" .equals (key)) {mos.write ("china", new Text ("China"), t) } else if ("American" .equals (key)) {mos.write ("usa", new Text ("American"), t);} else if ("Chinese" .equals (key)) {mos.write ("cpeople", new Text ("Chinese"), t) } / * * close MultipleOutputs; * / protected void cleanup (Context context) throws IOException, InterruptedException {mos.close ();}}

JobTest.java

Package com.xr.text;import java.io.IOException;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import org.apache.hadoop.mapreduce.lib.output.MultipleOutputs;import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat Public class JobTest {public static void main (String [] args) throws IOException, InterruptedException, ClassNotFoundException {String inputPath = "hdfs://192.168.75.100:9000/1.txt"; String outputPath = "hdfs://192.168.75.100:9000/ceshi"; Job job = new Job (); job.setJarByClass (JobTest.class) Job.setMapperClass (MyMapper.class); / * * set MultipleOutput file name * / MultipleOutputs.addNamedOutput (job, "china", TextOutputFormat.class, Text.class, Text.class); MultipleOutputs.addNamedOutput (job, "usa", TextOutputFormat.class, Text.class, Text.class) MultipleOutputs.addNamedOutput (job, "cpeople", TextOutputFormat.class, Text.class, Text.class); job.setReducerClass (MyReducer.class); job.setOutputKeyClass (Text.class); job.setOutputValueClass (Text.class); FileInputFormat.setInputPaths (job, new Path (inputPath)) / / Configuration conf = new Configuration (); / / FileSystem fs = FileSystem.get (conf); / if (fs.exists (new Path (outputPath) {/ / fs.delete (new Path (outputPath), true); / /} FileOutputFormat.setOutputPath (job, new Path (outputPath)) System.exit (job.waitForCompletion (true)? 0: 1);}}

An error is reported during operation:

14-08-12 12:44:02 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... Using builtin-java classes where applicable

12:44:02 on 14-08-12 ERROR security.UserGroupInformation: PriviledgedActionException as:Xr cause:java.io.IOException: Failed to set permissions of path:\ tmp\ hadoop-Xr\ mapred\ staging\ Xr-1514460710\ .stagi ng to 0700

Exception in thread "main" > java.io.IOException: Failed to set permissions of path:\ tmp\ hadoop-Xr\ mapred\ staging\ Xr-1514460710\ .staging to 0700

At org.apache.hadoop.fs.FileUtil.checkReturnValue (FileUtil.java:689)

At org.apache.hadoop.fs.FileUtil.setPermission (FileUtil.java:662)

At org.apache.hadoop.fs.RawLocalFileSystem.setPermission (RawLocalFileSystem.java:509)

At org.apache.hadoop.fs.RawLocalFileSystem.mkdirs (RawLocalFileSystem.java:344)

At org.apache.hadoop.fs.FilterFileSystem.mkdirs (FilterFileSystem.java:189)

At org.apache.hadoop.mapreduce.JobSubmissionFiles.getStagingDir (JobSubmissionFiles.java:116)

At org.apache.hadoop.mapred.JobClient$2.run (JobClient.java:918)

At org.apache.hadoop.mapred.JobClient$2.run (JobClient.java:912)

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:1149)

At org.apache.hadoop.mapred.JobClient.submitJobInternal (JobClient.java:912)

At org.apache.hadoop.mapreduce.Job.submit (Job.java:500)

At org.apache.hadoop.mapreduce.Job.waitForCompletion (Job.java:530)

At com.xr.text.JobTest.main (JobTest.java:37)

Error solution:

1. Delete the FileUtil.class from hadoop-core-1.1.2.jar.

two。 Then copy / org/apache/hadoop/fs/FileUtil.java from the source code

3. Comment on the checkReturnValue () method

The error is reported again at runtime:

Java.lang.OutOfMemoryError: Java heap space

Solution:

The ok,job was carried out smoothly.

Generate the following files:

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