I built an application with guidance of Pro Spring (integration with hibernate) running on tomcat, I runs well at first, till I run stress test, with submiting the form numbers of time.. then it returns
"could not execute query[SQL: 0, 08006]"
then the server stall.. I should restart the server.

Is this kind of problem is from hibernate or the tomcat itself?
if it's from hibernate, does anyone have idea how to solve it?

thx a lot.