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How to use the MultipleInput class in mapreduce?

I have one question.

I need two files to enter mapreduce.

@Override public int run(String[] args) throws Exception { (argument skip) Job job1 = new Job(); job1.setJarByClass(CFRecommenderDriver.class); job1.setMapperClass(CFRecommenderMapper.class); //job1.setReducerClass(CFRecommenderReducer.class); job1.setMapOutputKeyClass(Text.class); job1.setMapOutputValueClass(TextDoublePairWritableComparable.class); //job1.setOutputKeyClass(TextTwoWritableComparable.class); //job1.setOutputValueClass(TextDoubleTwoPairsWritableComparable.class); MultipleInputs.addInputPath(job1, new Path(args[0]), FileInputFormat.class); MultipleInputs.addInputPath(job1, new Path(args[1]), FileInputFormat.class); job1.setNumReduceTasks(0); boolean step1 = job1.waitForCompletion(true); if(!(step1)) return -1;

If I run the program with the following command:

 hadoop jar mapreduce-0.1.jar cf /input/cf-re/data1 /input/cf-re/data2 /output/cf-r/data1

I get the following error:

 2013-07-01 13:13:44.822 java[45783:1603] Unable to load realm info from SCDynamicStore 13/07/01 13:13:45 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same. 13/07/01 13:13:45 INFO mapred.JobClient: Cleaning up the staging area hdfs://127.0.0.1:9000/tmp/hadoop- suhyunjeon/mapred/staging/suhyunjeon/.staging/job_201306191432_0218 java.lang.RuntimeException: java.lang.InstantiationException at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115) at org.apache.hadoop.mapreduce.lib.input.MultipleInputs.getInputFormatMap(MultipleInputs.java:109) at org.apache.hadoop.mapreduce.lib.input.DelegatingInputFormat.getSplits(DelegatingInputFormat.java:58) at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:1024) at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:1041) at org.apache.hadoop.mapred.JobClient.access$700(JobClient.java:179) at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:959) at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:912) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1149) at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:912) at org.apache.hadoop.mapreduce.Job.submit(Job.java:500) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:530) at org.ankus.hadoop.mapreduce.algorithm.cf.recommender.CFRecommenderDriver.run(CFRecommenderDriver.java:86) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79) at org.ankus.hadoop.mapreduce.algorithm.cf.recommender.CFRecommenderDriver.main(CFRecommenderDriver.java:49) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68) at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139) at org.ankus.hadoop.mapreduce.MapReduceDriver.main(MapReduceDriver.java:64) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.hadoop.util.RunJar.main(RunJar.java:156) Caused by: java.lang.InstantiationException at sun.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:30) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:113) ... 29 more

I don’t know what exactly the problem is. Please help me.

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3 answers

You cannot use the abstract FileInputFormat class directly. If your entries are text, you can use org.apache.hadoop.mapreduce.lib.input.TextInputFormat . For instance,

 MultipleInputs.addInputPath(job1, new Path(args[0]), TextInputFormat.class); MultipleInputs.addInputPath(job1, new Path(args[1]), TextInputFormat.class);
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Here's how you can use multiple input files in your work:

 job1.setInputFormatClass(TextInputFormat.class); FileInputFormat.setInputPaths(job1, input_1 + "," + input_2);
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I think that it is worth mentioning another method that can be used to add several input paths, and, in my opinion, the most beautiful and simple: FileInputFormat.setInputPaths (Job job, Path ... inputPaths)

The Path... signature says that you can provide any number of Path objects for this call. Example:

 FileInputFormat.setInputPaths(job, new Path(args[0]), new Path(args[1]), new Path(args[2]));
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Source: https://habr.com/ru/post/1489029/

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