Tool for testing Functionality of an Application Server

Hello:

I have to test the functionality of an Application Server, which sometimes has problems when some SQL statements are executed when many users are using the same data and the data is getting lost. For that reason, I am looking for a tool that helps me to test the Application Server and find out what is causing those problems.

I have look for Functionality test tools, but all of them are for testing Web Applications based on Http requests, which is not my case because is an AppServer.

Could someone please give a hint what kind of test tool can I use for my AppServer? Or any idea of how I found out these errors without this Functionality tools?

Thank you in advance.

Regards,

Fiona