This code won't work if the json spans more than one line in the input files. On May 3, 2015 1:41 AM, "Shambhavi Punja" <[email protected]> wrote:
> Hi Shahab, > > Thanks. That helped. > > Regards, > Shambhavi > > On Thu, Apr 30, 2015 at 10:18 AM, Shahab Yunus <[email protected]> > 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 <[email protected]> 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. >>> >>> >> >
