Hello all,
I’m having an issue using AvroMultipleOutputs in a map/reduce job. The issue
occurs when using a schema that has a union of null and a fixed (among other
complex types), default to null, and it is not null. Please find the full
stack trace below and a sample map/reduce job that generates an Avro container
file and uses that for the m/r input. Note that I can serialize/deserialize
without issue using GenericDatumWriter/GenericDatumReader outside of hadoop…
Any insight would be helpful.
Stack trace:
java.lang.Exception: org.apache.avro.file.DataFileWriter$AppendWriteException:
java.lang.NullPointerException: in com.foo.bar.simple_schema in union null of
union in field baz of com.foo.bar.simple_schema
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:404)
Caused by: org.apache.avro.file.DataFileWriter$AppendWriteException:
java.lang.NullPointerException: in com.foo.bar.simple_schema in union null of
union in field baz of com.foo.bar.simple_schema
at org.apache.avro.file.DataFileWriter.append(DataFileWriter.java:296)
at
org.apache.avro.mapreduce.AvroKeyRecordWriter.write(AvroKeyRecordWriter.java:77)
at
org.apache.avro.mapreduce.AvroKeyRecordWriter.write(AvroKeyRecordWriter.java:39)
at
org.apache.avro.mapreduce.AvroMultipleOutputs.write(AvroMultipleOutputs.java:400)
at
org.apache.avro.mapreduce.AvroMultipleOutputs.write(AvroMultipleOutputs.java:378)
at
com.tts.ox.mapreduce.example.avro.AvroContainerFileDriver$SampleMapper.map(AvroContainerFileDriver.java:78)
at
com.tts.ox.mapreduce.example.avro.AvroContainerFileDriver$SampleMapper.map(AvroContainerFileDriver.java:62)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:140)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:672)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:330)
at
org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:266)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
Caused by: java.lang.NullPointerException: in com.foo.bar.simple_schema in
union null of union in field baz of com.foo.bar.simple_schema
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:145)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:58)
at org.apache.avro.file.DataFileWriter.append(DataFileWriter.java:290)
... 16 more
Caused by: java.lang.NullPointerException
at org.apache.avro.reflect.ReflectData.createSchema(ReflectData.java:457)
at org.apache.avro.specific.SpecificData.getSchema(SpecificData.java:189)
at org.apache.avro.reflect.ReflectData.isRecord(ReflectData.java:167)
at org.apache.avro.generic.GenericData.getSchemaName(GenericData.java:608)
at org.apache.avro.specific.SpecificData.getSchemaName(SpecificData.java:265)
at org.apache.avro.generic.GenericData.resolveUnion(GenericData.java:597)
at
org.apache.avro.generic.GenericDatumWriter.resolveUnion(GenericDatumWriter.java:151)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:71)
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:143)
at
org.apache.avro.generic.GenericDatumWriter.writeField(GenericDatumWriter.java:114)
at
org.apache.avro.reflect.ReflectDatumWriter.writeField(ReflectDatumWriter.java:175)
at
org.apache.avro.generic.GenericDatumWriter.writeRecord(GenericDatumWriter.java:104)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:66)
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:143)
Sample m/r job:
<mr_job>
package com.tts.ox.mapreduce.example.avro;
import org.apache.avro.Schema;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.generic.GenericRecordBuilder;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.mapred.AvroKey;
import org.apache.avro.mapreduce.AvroJob;
import org.apache.avro.mapreduce.AvroKeyInputFormat;
import org.apache.avro.mapreduce.AvroKeyOutputFormat;
import org.apache.avro.mapreduce.AvroMultipleOutputs;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import java.io.File;
import java.io.IOException;
public class AvroContainerFileDriver extends Configured implements Tool {
//
// define a schema with a union of null and fixed
private static final String SCHEMA = "{\n" +
" \"namespace\": \"com.foo.bar\",\n" +
" \"name\": \"simple_schema\",\n" +
" \"type\": \"record\",\n" +
" \"fields\": [{\n" +
" \"name\": \"foo\",\n" +
" \"type\": {\n" +
" \"name\": \"bar\",\n" +
" \"type\": \"fixed\",\n" +
" \"size\": 2\n" +
" }\n" +
" }, {\n" +
" \"name\": \"baz\",\n" +
" \"type\": [\"null\", \"bar\"],\n" +
" \"default\": null\n" +
" }]\n" +
"}";
public static class SampleMapper extends Mapper<AvroKey<GenericRecord>,
NullWritable, NullWritable, NullWritable> {
private AvroMultipleOutputs amos;
@Override
protected void setup(Context context) {
amos = new AvroMultipleOutputs(context);
}
@Override
protected void cleanup(Context context) throws IOException,
InterruptedException {
amos.close();
}
@Override
protected void map(AvroKey<GenericRecord> record, NullWritable ignore,
Context context)
throws IOException, InterruptedException {
// simply write the record to a container using AvroMultipleOutputs
amos.write("avro", new AvroKey<GenericRecord>(record.datum()),
NullWritable.get());
}
}
@Override
public int run(final String[] args) throws Exception {
Schema.Parser parser = new Schema.Parser();
Schema schema = parser.parse(SCHEMA);
//
// generate avro container file for input to mapper
byte[] dummy = {(byte) 0x01, (byte) 0x02};
GenericData.Fixed foo = new
GenericData.Fixed(schema.getField("foo").schema(), dummy);
GenericData.Fixed baz = new
GenericData.Fixed(schema.getField("baz").schema().getTypes().get(1), dummy);
GenericRecordBuilder builder = new GenericRecordBuilder(schema)
.set(schema.getField("foo"), foo);
GenericRecord record0 = builder.build(); // baz is null
builder.set(schema.getField("baz"), baz);
GenericRecord record1 = builder.build(); // baz is not null, bad news
File file = new File("/tmp/avrotest/input/test.avro");
DatumWriter<GenericRecord> datumWriter = new
GenericDatumWriter<GenericRecord>(schema);
DataFileWriter<GenericRecord> dataFileWriter = new
DataFileWriter<GenericRecord>(datumWriter);
dataFileWriter.create(schema, file);
dataFileWriter.append(record0);
//
// HELP: job succeeds when we do not have record with non-null baz,
comment out to succeed
//
dataFileWriter.append(record1);
dataFileWriter.close();
//
// configure and run job
Configuration configuration = new Configuration();
String[] otherArgs = new GenericOptionsParser(configuration,
args).getRemainingArgs();
Job job = Job.getInstance(configuration, "Sample Avro Map Reduce");
job.setInputFormatClass(AvroKeyInputFormat.class);
AvroJob.setInputKeySchema(job, schema);
job.setMapperClass(SampleMapper.class);
job.setNumReduceTasks(0);
AvroJob.setOutputKeySchema(job, schema);
AvroMultipleOutputs.addNamedOutput(job, "avro",
AvroKeyOutputFormat.class, schema);
FileInputFormat.addInputPath(job, new Path(("/tmp/avrotest/input")));
FileOutputFormat.setOutputPath(job, new Path("/tmp/avrotest/output"));
return (job.waitForCompletion(true) ? 0 : 1);
}
public static void main(String[] args) throws Exception {
int exitCode = ToolRunner.run(new AvroContainerFileDriver(), args);
System.exit(exitCode);
}
}
</mr_job>
Thanks,
John Pauley
Sr. Software Engineer
ThreatTrack Security
