You can look at the mode in which the stored procedure or package is pinned in the library cache. This information is in X$KGLOB.KGLHDPMD. A value of 2 indicates that the object is pinned in shared mode by one or more sessions. If necessary, you can join to X$KGLPN to find the sessions holding the pins. See executing_packages.sql for an example.

How can I tell if a stored procedure or package is in the middle of execution?