[HIVEMALL-296][BUGFIX] Fixed corner case NPE bug when count is zero

## What changes were proposed in this pull request?

Fixed corner case NPE bug when count is zero.

```
Caused by: java.lang.NullPointerException
	at hivemall.GeneralLearnerBaseUDTF.forwardModel(GeneralLearnerBaseUDTF.java:763)
	at hivemall.GeneralLearnerBaseUDTF.close(GeneralLearnerBaseUDTF.java:560)
	at org.apache.hadoop.hive.ql.exec.UDTFOperator.closeOp(UDTFOperator.java:152)
	at org.apache.hadoop.hive.ql.exec.Operator.close(Operator.java:697)
	at org.apache.hadoop.hive.ql.exec.Operator.close(Operator.java:711)
	at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.close(ExecReducer.java:279)
```

## What type of PR is it?

Bug Fix

## What is the Jira issue?

https://issues.apache.org/jira/browse/HIVEMALL-296

## How was this patch tested?

unit tests

## Checklist

- [x] Did you apply source code formatter, i.e., `./bin/format_code.sh`, for your commit?
- [ ] Did you run system tests on Hive (or Spark)?

Author: Makoto Yui <myui@apache.org>

Closes #230 from myui/HIVEMALL-296.
2 files changed
tree: ad02a576158cd46ea1ca9c77e2fc6ba4a5f71ff8
  1. .github/
  2. bin/
  3. conf/
  4. core/
  5. dist/
  6. docs/
  7. mixserv/
  8. nlp/
  9. resources/
  10. src/
  11. tools/
  12. xgboost/
  13. .dockerignore
  14. .gitignore
  15. .rat-excludes
  16. .travis.yml
  17. ChangeLog.md
  18. DISCLAIMER
  19. KEYS
  20. LICENSE
  21. NOTICE
  22. pom.xml
  23. README.md
  24. VERSION
README.md

Apache Hivemall: Hive scalable machine learning library

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Apache Hivemall is a scalable machine learning library that runs on Apache Hive, Apache Spark, and Apache Pig. Hivemall is designed to be scalable to the number of training instances as well as the number of training features.

Usage

Hivemall

Find more examples on our user guide and find a brief introduction to Hivemall in this slide.

Support

Support is through user@hivemall.incubator.apache.org, not by a direct e-mail.

Contributing

If you are planning to contribute to this repository, we first request you to create an issue at our JIRA page even if the topic is not related to source code itself (e.g., documentation, new idea and proposal).

All Hivemall functions are defined under resources/ddl. In order to update the definition files, the following script helps inserting function name and class path of your new UDF:

$ ./bin/update_ddls.sh

Moreover, don't forget to update function list in the document as well:

$ ./bin/update_func_md.sh

Note that, before creating a pull request including Java code, please make sure your code follows our coding conventions by applying formatter:

$ ./bin/format_code.sh