How can I troubleshoot which processes are keeping connections open?
Background: A QA installation of several software components is generating an ORA-12516 error now and then, and I'm not sure which component is at fault. The DBA raised the value of PROCESSES and things are working fine, but I'd like to understand where the surprising number of connections is coming from.
(Am I keeping some open when I shouldn't? Is there a rogue process in the QA environment? Etc.)
Assuming I'm not able to instrument the clients which open up connections, can I interrogate the database or its logs? If so, how?