SPARK-10474 (https://github.com/apache/spark/pull/8888) removed the pointer array tracking because `TungstenAggregate` would fail under memory pressure. However, this is somewhat of a hack that we should fix in the right way in 1.6.0 to ensure we don't OOM because of this.
is related to
SPARK-10474TungstenAggregation cannot acquire memory for pointer array after switching to sort-based
SPARK-10929Tungsten fails to acquire memory writing to HDFS