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From Blanca Hernandez <Blanca.Hernan...@willhaben.at>
Subject ClassCastException on running map-reduce jobs + tests on Windows (mongo-hadoop)
Date Wed, 17 Sep 2014 13:26:39 GMT

I am getting some CCE and donĀ“t really understand why...

Here my mapper:

public class AveragePriceMapper extends Mapper<String, BSONObject, String, BSONObject>{
    public void map(final String key, final BSONObject val, final Context context) throws
IOException, InterruptedException {
        String id = "result_of_making_some_operations";
        context.write(id, val);

And in my configuration:


On running my generated jar on the server, seems to work everything ok until:

14/09/17 15:20:36 INFO mapred.MapTask: Processing split: MongoInputSplit{URI=mongodb://user:pass@host:27017/my_db.my_collection,
authURI=null, min={ "_id" : { "$oid" : "541666d8e4b07265e257a42e"}}, max={ }, query={ }, sort={
}, fields={ }, notimeout=false}
14/09/17 15:20:36 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
14/09/17 15:20:36 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
14/09/17 15:20:36 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
14/09/17 15:20:36 INFO mapred.MapTask: soft limit at 83886080
14/09/17 15:20:36 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
14/09/17 15:20:36 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
14/09/17 15:20:36 INFO mapred.LocalJobRunner: map task executor complete.
14/09/17 15:20:36 WARN mapred.LocalJobRunner: job_local1701078621_0001java.lang.Exception:
java.lang.ClassCastException: class java.lang.String
        at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
        at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ClassCastException: class java.lang.String
        at java.lang.Class.asSubclass(Class.java:3126)
        at org.apache.hadoop.mapred.JobConf.getOutputKeyComparator(JobConf.java:885)
        at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.init(MapTask.java:981)
        at org.apache.hadoop.mapred.MapTask.createSortingCollector(MapTask.java:391)
        at org.apache.hadoop.mapred.MapTask.access$100(MapTask.java:80)
        at org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:675)
        at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:747)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
        at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
        at java.util.concurrent.FutureTask.run(FutureTask.java:262)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:744)

Did I miss something??

Another issue I am worry about: working on a Windows system makes everything quite complicated
with Hadoop. I have it installed and running, the same as my mongoDB database (I am using
the connector provided by them). Running the same main class I am using in the hadooop jar
call on the server (in the example before), but from my IDE, I get this exception:

PriviledgedActionException as:hernanbl cause:java.io.IOException: Failed to set permissions
of path: \tmp\hadoop-hernanbl\mapred\staging\hernanbl1600842219\.staging to 0700

How could I make it run?

Many thanks!!

Best regards,


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