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From Shambhavi Punja <spu...@usc.edu>
Subject Re: Json Parsing in map reduce.
Date Fri, 01 May 2015 21:35:51 GMT
Hi Shahab,

Thanks. That helped.

Regards,
Shambhavi

On Thu, Apr 30, 2015 at 10:18 AM, Shahab Yunus <shahab.yunus@gmail.com>
wrote:

> 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 <spunja@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.
>>
>>
>

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