1.9.3. Limitations of Map Methods

Specific Map methods, such as size(), values(), keySet() and entrySet(), can be used with certain limitations with JBoss Data Grid as they are unreliable. These methods do not acquire locks (global or local) and concurrent modification, additions and removals are excluded from consideration in these calls. Furthermore, the listed methods are only operational on the local data container and do not provide a global view of state.
If the listed methods acted globally, it would result in a significant impact on performance and would produce a scalability bottleneck. As a result, it is recommended that these methods are used for informational and debugging purposes only.