Reduce your memory usage with Hibernate's evict

I was running low on memory when performing an operation for all Employee objects of my Company object. Since the operation performed changes on a big hashmap, deep inside my Employee object, I noticed that the operation on subsequent employees took more and more time, until the application finally ran out of memory.

I fixed this by fetching a hibernate iterator and evicting my Employee object when my operation was done.


Iterator userIterator = userRepository.getUserIterator(company);
while(userIterator.hasNext()){
   User user = userIterator.next();
   user.getEmployee().openYearForBookings(holidayYear);
   userRepository.flush();
   userRepository.evict(user);
}


Sorry for the flush, but when not flushing the session before the evict, I lost all changes made to the evicted object.