Open Source Application Server Comparison

Things to consider when choosing open source application servers

•Load balancing: random; minimum load; round-robin; weighted round-robin; performance-based; load-based; dynamic algorithm based; dynamic registration.
•Clustering & HA. Additionally: distributed transaction management; in-memory replication of session state information; no single point of failure.
•Connection pooling.
•Caching. JNDI caching. Distributed caching with synchronization.
•Thread pooling.
•Configurable user Quality of Service.
•Analysis tools.
•Low system/memory requirements.
•Optimized subsystems (RMI, JMS, JDBC drivers, JSP tags & cacheable page fragments).
•Optimistic transaction support.

Wikipedia Comparision

Openlogic (Summary | Full)