The scope of EntityGraph should be persistence unit, not persistence context.
The method such as EntityManager.createEntityGraph(String name) etc. looks non-intuitive. If an application wants to create a graph at runtime, it should call EntityManagerFactory.createEntityGraph(String name).
As the API currently stands, it seems to allow EntityGraph of the same name be defined by two separate persistence contexts -- opening up a pandora's box of confusion. It is much safer to define these graphs scoped at EntityManagerFactory level and imposing uniqueness on the name of the graphs.
Chair, Apache OpenJPA Project http://openjpa.apache.org/
JPA Expert Group Member
Application & Integration Middleware
[jpa-spec users] [jsr338-experts] scope of EntityGraphs