apache/spark — pull request #3690 by srowen (2014-12-14 01:10:14+00:00)
Title: SPARK-785 [CORE] ClosureCleaner not invoked on most PairRDDFunctions

This looked like perhaps a simple and important one. `combineByKey` looks like it should clean its arguments' closures, and that in turn covers apparently all remaining functions in `PairRDDFunctions` which delegate to it.