The concept of regions and the Region class were visited earlier when talking about marshalling. Regions also have another use, in that they are used to define the eviction policy used within the region. In addition to using a region-specific configuration, you can also configure a default, cache-wide eviction policy for nodes that do not fall into predefined regions or if you do not wish to define specific regions. It is important to note that when defining regions using the configuration XML file, all elements of the Fqn that defines the region are java.lang.String objects.

Looking at the eviction configuration snippet above, we see that a default region, _default_ , holds attributes which apply to nodes that do not fall into any of the other regions defined.

For each region, you can define parameters which affect how the policy which applies to the region chooses to evict nodes. In the example above, the LRUPolicy allows a maxNodes parameter which defines how many nodes can exist in the region before it chooses to start evicting nodes. See the javadocs for each policy for a list of allowed parameters. It also defines a minTimeToLiveSeconds parameter, which defines a minimum time a node must exist in memory before being considered for eviction.