Yes, I went through this post already. Pool size is min 10 and max 50. <blocking-timeout-millis> is 30000 milli seconds which I have not changed. I did not change it because my application was running fine from last 2 years. Only now we are facing this issue. There is no major change in my application which can cause this issue. We are closing connections every where we open it. One clue is, I could see deadlocks happening before this exception happened. There is one SP which will be run by 5 to 6 threads same time. This might have caused deadlocks. My application handles deadlock issues properly (We couldn't avoid it). Is there any leak in the pool when a deadlock happens? connection.close() we call in finally block always. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4149884#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...