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https://issues.apache.org/jira/browse/CRUNCH-601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15425423#comment-15425423
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Mikael Goldmann commented on CRUNCH-601:
----------------------------------------
Regrettably, this test will still fail because the getSize() returns 0.
{code}
@Test
public void sizeEstimateZero() throws Exception {
Pipeline p = new SparkPipeline("local", "foobar");
try {
final PCollection<String> collection =
p.emptyPCollection(Avros.strings()).parallelDo(new DoFn<String,
String>() {
@Override
public void process(String input, Emitter<String> emitter) {
emitter.emit(input);
}
@Override
public void cleanup(Emitter<String> emitter) {
emitter.emit("apelsin");
}
}, Avros.strings());
final PObject<Long> length = collection.length();
p.run();
assertThat(length.getValue(), is(1L));
}finally {
p.done();
}
}
{code}
The reson being that only the empty collection contributes to the size estimate.
> Short PCollections in SparkPipeline get length null.
> ----------------------------------------------------
>
> Key: CRUNCH-601
> URL: https://issues.apache.org/jira/browse/CRUNCH-601
> Project: Crunch
> Issue Type: Bug
> Components: Spark
> Affects Versions: 0.13.0
> Environment: Running in local mode on Mac as well as in a ubuntu
> 14.04 docker container
> Reporter: Mikael Goldmann
> Priority: Minor
> Attachments: CRUNCH-601.patch, SmallCollectionLengthTest.java
>
>
> I'll attach a file with a test that I would expect to pass but which fails.
> It creates five PCollection<String> of lengths 0, 1, 2, 3, 4 gets the
> lengths, runs the pipeline and prints the lengths. Finally it asserts that
> all lengths are non-null.
> I would expect it to print lengths 0, 1, 2, 3, 4 and pass.
> What it does is print lengths null, null, null, 3, 4 and fail.
> I think the underlying reason is the use of getSize() on an unmaterialized
> object and assuming that when the estimate that getSize() returns is 0, then
> the PCollection is guaranteed to be empty, which is false in some cases.
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