The reason is that the Json parsing code is in a 3rd party library which is not included in the default map reduce/hadoop distribution. You have to add them in your classpath at *runtime*. There are multiple ways to do it (which also depends upon how you plan to run and package/deploy your code.)
Check out this: https://hadoopi.wordpress.com/2014/06/05/hadoop-add-third-party-libraries-to-mapreduce-job/ http://blog.cloudera.com/blog/2011/01/how-to-include-third-party-libraries-in-your-map-reduce-job/ Regards, Shahab On Thu, Apr 30, 2015 at 1:01 PM, Shambhavi Punja <spu...@usc.edu> wrote: > Hi, > > I am working on an assignment on Hadoop Map reduce. I am very new to Map > Reduce. > > The assignment has many sections but for now I am trying to parse JSON > data. > > The input(i.e. value) to the map function is a single record of the form > xyz, {'abc’:’pqr1’,'abc2’:'pq1, pq2’}, {‘key’:'value1’} > I am interested only in the getting the frequency of value1. > > Following is the map- reduce job. > > public static class Map extends MapReduceBase implements > Mapper<LongWritable, Text, Text, IntWritable> { > private final static IntWritable one = new IntWritable(1); > private Text word = new Text(); > > > public void map(LongWritable key, Text value, > OutputCollector<Text, IntWritable> output, Reporter reporter) throws > IOException { > String line = value.toString(); > String[] tuple = line.split("(?<=\\}),\\s"); > try{ > JSONObject obj = new JSONObject(tuple[1]); > String id = obj.getString(“key"); > word.set(id); > output.collect(word, one); > } > catch(JSONException e){ > e.printStackTrace(); > } > } > } > > > > > public static class Reduce extends MapReduceBase implements > Reducer<Text, IntWritable, Text, IntWritable> { > public void reduce(Text key, Iterator<IntWritable> values, > OutputCollector<Text, IntWritable> output, Reporter reporter) throws > IOException { > int sum = 0; > while (values.hasNext()) { > sum += values.next().get(); > } > output.collect(key, new IntWritable(sum)); > } > } > > I successfully compiled the java code using the json and hadoop jars. > Created a jar. But wen I run the Hadoop command I am getting the following > exceptions. > > > 15/04/30 00:36:49 WARN util.NativeCodeLoader: Unable to load native-hadoop > library for your platform... using builtin-java classes where applicable > 15/04/30 00:36:49 WARN mapred.JobClient: Use GenericOptionsParser for > parsing the arguments. Applications should implement Tool for the same. > 15/04/30 00:36:49 WARN snappy.LoadSnappy: Snappy native library not loaded > 15/04/30 00:36:49 INFO mapred.FileInputFormat: Total input paths to > process : 1 > 15/04/30 00:36:49 INFO mapred.JobClient: Running job: > job_local1121514690_0001 > 15/04/30 00:36:49 INFO mapred.LocalJobRunner: Waiting for map tasks > 15/04/30 00:36:49 INFO mapred.LocalJobRunner: Starting task: > attempt_local1121514690_0001_m_000000_0 > 15/04/30 00:36:49 INFO mapred.Task: Using ResourceCalculatorPlugin : null > 15/04/30 00:36:49 INFO mapred.MapTask: Processing split: > file:/Users/Shamvi/gumgum/jars/input/ab1.txt:0+305 > 15/04/30 00:36:49 INFO mapred.MapTask: numReduceTasks: 1 > 15/04/30 00:36:49 INFO mapred.MapTask: io.sort.mb = 100 > 15/04/30 00:36:49 INFO mapred.MapTask: data buffer = 79691776/99614720 > 15/04/30 00:36:49 INFO mapred.MapTask: record buffer = 262144/327680 > 15/04/30 00:36:49 INFO mapred.LocalJobRunner: Map task executor complete. > 15/04/30 00:36:49 WARN mapred.LocalJobRunner: job_local1121514690_0001 > java.lang.Exception: java.lang.RuntimeException: Error in configuring > object > at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:354) > Caused by: java.lang.RuntimeException: Error in configuring object > at > org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:93) > at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:64) > at > org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:117) > at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:426) > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:366) > at > org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:223) > at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) > at java.util.concurrent.FutureTask.run(FutureTask.java:266) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) > at java.lang.Thread.run(Thread.java:745) > Caused by: java.lang.reflect.InvocationTargetException > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > at > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:483) > at > org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:88) > ... 10 more > Caused by: java.lang.NoClassDefFoundError: org/json/JSONException > at java.lang.Class.forName0(Native Method) > at java.lang.Class.forName(Class.java:344) > at > org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:810) > at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:855) > at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:881) > at org.apache.hadoop.mapred.JobConf.getMapperClass(JobConf.java:968) > at org.apache.hadoop.mapred.MapRunner.configure(MapRunner.java:34) > ... 15 more > Caused by: java.lang.ClassNotFoundException: org.json.JSONException > at java.net.URLClassLoader$1.run(URLClassLoader.java:372) > at java.net.URLClassLoader$1.run(URLClassLoader.java:361) > at java.security.AccessController.doPrivileged(Native Method) > at java.net.URLClassLoader.findClass(URLClassLoader.java:360) > at java.lang.ClassLoader.loadClass(ClassLoader.java:424) > at java.lang.ClassLoader.loadClass(ClassLoader.java:357) > ... 22 more > 15/04/30 00:36:50 INFO mapred.JobClient: map 0% reduce 0% > 15/04/30 00:36:50 INFO mapred.JobClient: Job complete: > job_local1121514690_0001 > 15/04/30 00:36:50 INFO mapred.JobClient: Counters: 0 > 15/04/30 00:36:50 INFO mapred.JobClient: Job Failed: NA > Exception in thread "main" java.io.IOException: Job failed! > at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1357) > at org.myorg.Wordcount.main(Wordcount.java:64) > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > at > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:483) > at org.apache.hadoop.util.RunJar.main(RunJar.java:160) > > > PS: When I modify the same code and exclude the JSON parsing i.e. find > frequency of {‘key’:’value1’} section of the example input, all works well. > >
