Lucene 2.9 Introduced numerous enhancements into how the FieldCache is used by the low levels of Lucene searching (for Sorting and ValueSourceQueries) to improve both the speed for Sorting, as well as reopening of IndexReaders. But these changes have shifted the usage of FieldCache from "top level" IndexReaders (frequently a MultiReader or DirectoryReader) down to the leaf level SegmentReaders. As a result, existing applications that directly access the FieldCache may find RAM usage increase significantly when upgrading to 2.9 or Later. this class provides an API for these applications (or their Unit tests) to check at run time if the FieldCache contains "insane" usages of the FieldCache.
@lucene.experimental