A model of a software system under execution including: a representation
of a first node corresponding to a first function executing in the
software system which obtains access to a resource, with an indicator of
a number of times the first function has been called in the software
system; a representation of a second node corresponding to a second
function executing in the software system while the resource is accessed,
with an indicator of a number of times the second function has been
called; a representation of a place holder node with an indicator that
the place holder node has never been called in the software system; a
representation of a first call from the first node to the place holder
node; and a representation of a second call from the place holder node to
the second node. The first and second calls correspond to the first
function calling the second function in the software system.