Why ConcurrentHashMap cannot be locked for exclusive access?

Question

A quote from #JCIP :

\"Since a ConcurrentHashMap cannot be locked for exclusive access, we cannot use client-side locking to create new atomic operatio

Answer 1

Why? Because the implementation does not support it. Straight from the ConcurrentHashMap JavaDocs:

There is not any support for locking the entire table in a way that prevents all access

...which is, by definition, "exclusive access."