Hi,
I actually came across a particular case I'm not sure whether the behavior
is right or not. So here is what is happening I am getting No Output
exception throwing while trying to run my Crunch job. On further
investigating I found that I was using Pipeline.emptyCollection(). So here
is how my scenario looks like
PCollection<V> collectionWhichCouldBeEmpty = null;
if(path.exists){
collectionWhichCouldBeEmpty= pipeline.read(FromPath, PType.V);
} else{
collectionWhichCouldBeEmpty = pipeline.emptyPCollection();
}
//do some operations
pipeline.write(Target);
pipeline.run()// this is where it is throwing the error
https://github.com/apache/crunch/blob/master/crunch-core/src/main/java/org/apache/crunch/impl/mr/plan/MSCRPlanner.java#L287
On further debugging I found that the Vertex didn't have an input.
https://github.com/apache/crunch/blob/master/crunch-core/src/main/java/org/apache/crunch/impl/mr/plan/MSCRPlanner.java#L275
So If I use the pipeline.read and it creates an Empty PCollection it works
since it has the input source but If I create an Empty PCollection using
the pipeline.emptyPCollection which doesn't have an input source then it
fails
Not sure if the case is missed or it has to be like this.
Thanks
Jinal
