Hi all,
I had a join step in my crunch pipeline, and it looks like the
following:
//get label data
PType<Labels> LabelsType = Avros.records(Labels.class);
PCollection<Labels> training_labels = input.parallelDo(new
LabelDataParser(), LabelsType);
PTable<String, Labels> labels_data = training_labels.
parallelDo(new KeyOnLabels("sample_ID"), tableOf(strings(), LabelsType));
//get features
PType<Feats> FeatsType = Avros.records(Feats.class);
PCollection<Feats> training_feats = Feature.FeatLoader(pipeline,
sample_features_inputs);
PTable<String, Feats> feats_data = training_feats.parallelDo(new KeyOnFeats(
"sample_ID"), tableOf(strings(), FeatsType));
//join labels and features
JoinStrategy<String, Labels, Feats> strategy = new
DefaultJoinStrategy<String, Labels, Feats>(20);
PTable<String, Pair<Labels, Feats>> joined_training = strategy.
join(labels_data, feats_data, JoinType.INNER_JOIN);
//class Labels
public class Labels implements java.io.Serializable, Cloneable{
private String class_ID;
private String sample_ID;
private int binary_ind;
public Labels()
{
this(null, null, 0);
}
public Labels(String class_ID, String sample_ID, int ind)
{
this.class_ID = class_ID;
this.sample_ID = sample_ID;
this.binary_ind = ind;
}
...
}
//class Feats
public class *Feats* implements java.io.Serializable, Cloneable{
private String sample_id;
private String sample_name;
private Map<String, Float> feat;
public Feats()
{
this(null, null, null);
}
public Feats(String id, String name, Map<String, Float> feat)
{
this.sample_id = id;
this.sample_name = name;
this.feat = feat;
}
...
}
The outputs of labels_data and feats_data are both fine; but the join
step throws the following exception:
Error: java.lang.ClassCastException: java.lang.String cannot be cast to
org.apache.crunch.Pair at
org.apache.crunch.lib.join.DefaultJoinStrategy$1.map(DefaultJoinStrategy.java:87)
at org.apache.crunch.MapFn.process(MapFn.java:34) at
org.apache.crunch.impl.mr.run.RTNode.process(RTNode.java:98) at
org.apache.crunch.impl.mr.emit.IntermediateEmitter.emit(IntermediateEmitter.java:56)
at org.apache.crunch.MapFn.process(MapFn.java:34) at
org.apache.crunch.impl.mr.run.RTNode.process(RTNode.java:98) at
org.apache.crunch.impl.mr.run.RTNode.process(RTNode.java:109) at
org.apache.crunch.impl.mr.run.CrunchMapper.map(CrunchMapper.java:60) at
org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145) at
org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763) at
org.apache.hadoop.mapred.MapTask.run(MapTask.java:339) at
org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:162) at
java.security.AccessController.doPrivileged(Native Method) at
javax.security.auth.Subject.doAs(Subject.java:415) at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1491)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:157)
This issue already bothered me for a while; Did any one get a
similar issue here? Is there another option that will solve it?
Btw, I already successfully ran the following joining job:
JoinStrategy<String, Float, Tuple3<String, String, Float>> strategy = new
DefaultJoinStrategy<String, Float, Tuple3<String, String, Float>>(100);
PTable<String, Pair<Float,Tuple3<String, String, Float>>> joined =
strategy.join(input_A, input_B, JoinType.INNER_JOIN);
So I guess the issue may be still related to the Avro types that I
defined.
Thanks for your advice.
Lucy
