Not using ThreadLocal anymore, no performance reason and tricky (ThreadPooling for example).

By batch I mean mono transaction, see https://bitbucket.org/fryske-akademy/crudapi/src/1b81a53c154d97cb8a5c48fc4a61f6a73f4cba44/ejbCrudApi/src/main/java/org/fryske_akademy/ejb/CrudWriteService.java#lines-79

this does have a substantial influence on performance, in our case we have sheets (tables) from which multiple entities are saved in one go.