The documentation provided in NiFi does not include enough information on the default limitations of Java 7 that can offer result in Out of Memory: Permgen conditions. The Admin Guide should be updated in 2 places:
1. under system Requirements we should add a note about using Java 7 and point them to additional guidance under the bootstrap properties section.
2, In the bootstrap properties section we should document the commented out java 7 properties in the file and explain why they should have they should be used when running with Java 7.
Further, the codecache issues present in Java 7 and Java 8 also warrant commentary as the results can be terrible and extremely hard to figure out.