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From Florin Tatu <tatuflo...@gmail.com>
Subject Error while trying to obtain the top elements.
Date Tue, 07 Jul 2015 07:43:07 GMT
Hi,

I am having a job that processes a set of files containing climatic
data(more exactly data from this location:
ftp://ftp.ncdc.noaa.gov/pub/data/noaa/)

I downloaded and merged the data using a script so I will have one folder
(ncdc_data) having a .gz archive for each year(eg: 1901.gz, 1902.gz etc)
Each archive contains only one text file.

My code is:

import com.google.common.base.Charsets;
import com.google.common.io.Files;
import org.apache.crunch.*;
import org.apache.crunch.fn.Aggregators;
import org.apache.crunch.impl.mr.MRPipeline;
import org.apache.crunch.io.To;
import java.io.File;
import static org.apache.crunch.types.writable.Writables.ints;
import static org.apache.crunch.types.writable.Writables.strings;
import static org.apache.crunch.types.writable.Writables.tableOf;

public class MaxTemperatureCrunch {

    public static void main(String[] args) throws Exception {
        if (args.length != 2) {
            System.err.println("Usage: MaxTemperatureCrunch <input path>
<output path>");
            System.exit(-1);
        }

        Pipeline pipeline = new MRPipeline(MaxTemperatureCrunch.class);

        PCollection<String> records = pipeline.readTextFile(args[0]);

        PTable<String, Integer> yearTemperatures = records
                .parallelDo(toYearTempPairsFn(), tableOf(strings(),
ints()));

        PTable<String, Integer> maxTemps = yearTemperatures
                .groupByKey()
                .combineValues(Aggregators.MAX_INTS())
                .top(1);   //LINE THAT CAUSES THE ERROR

        maxTemps.write(To.textFile(args[1]));

        PipelineResult result = pipeline.done();
        String dot =
pipeline.getConfiguration().get("crunch.planner.dotfile");
        Files.write(dot, new File("pipeline.dot"), Charsets.UTF_8);
        Runtime.getRuntime().exec("dot -Tpng -O pipeline.dot");
        System.exit(result.succeeded() ? 0 : 1);
    }

    static DoFn<String, Pair<String, Integer>> toYearTempPairsFn() {
        return new DoFn<String, Pair<String, Integer>>() {
            NcdcRecordParser parser = new NcdcRecordParser();
            @Override
            public void process(String input, Emitter<Pair<String,
Integer>> emitter) {
                parser.parse(input);
                if (parser.isValidTemperature()) {
                    emitter.emit(Pair.of(parser.getYear(),
parser.getAirTemperature()));
                }
            }
        };
    }
}


Hadoop runs locally in standalone mode.
Hadoop version is: 2.7.0
Crunch version is: 0.12.0  (maven dependency: 0.12.0-hadoop2)

I build my application with: mvn package
I run it with: hadoop jar target/crunch-demo-1.0-SNAPSHOT-job.jar
ncdc_data/ output

If I do not call .top(1) (see comment:  //LINE THAT CAUSES THE ERROR)
everything works fine, but I obtain the maximum temperatures for each year
only and I want to obtain the overall maximum temperature or the top N
temperatures for the whole data set.

If I call .top(1) I obtain the following error:

java.lang.Exception: org.apache.crunch.CrunchRuntimeException: Error
reloading writable comparable codes
at
org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: org.apache.crunch.CrunchRuntimeException: Error reloading
writable comparable codes
at
org.apache.crunch.types.writable.TupleWritable.setConf(TupleWritable.java:71)
at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:76)
at
org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:136)
at
org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:66)
at
org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.deserialize(WritableSerialization.java:42)
at
org.apache.hadoop.io.SequenceFile$Reader.deserializeValue(SequenceFile.java:2247)
at
org.apache.hadoop.io.SequenceFile$Reader.getCurrentValue(SequenceFile.java:2220)
at
org.apache.hadoop.mapreduce.lib.input.SequenceFileRecordReader.nextKeyValue(SequenceFileRecordReader.java:78)
at
org.apache.crunch.impl.mr.run.CrunchRecordReader.nextKeyValue(CrunchRecordReader.java:157)
at
org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:556)
at
org.apache.hadoop.mapreduce.task.MapContextImpl.nextKeyValue(MapContextImpl.java:80)
at
org.apache.hadoop.mapreduce.lib.map.WrappedMapper$Context.nextKeyValue(WrappedMapper.java:91)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
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:745)
Caused by: java.lang.ClassNotFoundException:
org.apache.crunch.types.writable.TupleWritable
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:274)
at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:625)
at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1612)
at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1517)
at java.io.ObjectInputStream.readClass(ObjectInputStream.java:1483)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1333)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at
com.google.common.collect.Serialization.populateMap(Serialization.java:91)
at com.google.common.collect.HashBiMap.readObject(HashBiMap.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at
org.apache.crunch.types.writable.Writables.reloadWritableComparableCodes(Writables.java:145)
at
org.apache.crunch.types.writable.TupleWritable.setConf(TupleWritable.java:69)
... 20 more


Did anyone encountered this issue?
If you need any other details please ask me.

Thank you,
Florin

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