Thx for your answer.
Actually, my app isnt in production yet. In time, i'm just tunning jboss before that.
so... im using jmeter to stress my aplication and a have to achieve 300 simultaneous access, but for now when it takes 120 the error appears.
Im using 2 JBoss. Each JBoss have 1 instance running. In other server i have 1 Apache Web Server(mod_cluster) and the PostgreSQL.
In my datasources i have a max-pool-size with 500(for each JBoss instance, so i have 1000 connections).
PS: In PostgreSQL, has no limit connection.
Any help?