The AS 5 clustered webapp session passivation feature is not very useful when FIELD is used, since the pojos stored in the sessions are not part of the session 's part of the JBoss Cache tree. They are in an internal area that is a sibling to the sessions.[1] So, evicting the session tree does not evict the pojos. Presumably most of the memory is used by the pojos.

Solution is for JBossCacheManager to programatically establish a regular JBC eviction region for the pojo storage area. To configure this the following elements will be added to jboss-web.xml's passivation-config:

<passivation-config>
<max-objects>10</max-objects>
<object-max-idle-time>600</object-max-idle-time>
<passivation-config>

These values will be translated into the JBC LRUPolicy's "maxNodes" and "timeToLiveSeconds" configuration properties.

[1] They are in a sibling area to the sessions since the pojos can be shared between sessions. The pojos are scoped to the webapp.