Latest update: Thanks to Clebert, I managed to run ConnectionTest.testManyConnections by itself. The test is simply createConnection()/close() in a loop, 1000 times. I then looked at the logs it produces, and from there it looks like the client makes 300 connections successfully, and blocks on the 301st indefinitely. What could be the reason? I already tried applying the modification Kevin Conner described in http://www.jboss.com/index.html?module=bb&op=viewtopic&t=103695 but it didn't help. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4028485#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...