Linear typing schemes guarantee single-threadedness and so the soundness of in-place update with respect to a functional semantics. But linear

This thesis presents a system for specifying constraints on dynamically changing referencing relationships of heap objects, and an analysis for static verification of these constraints. The constraint specification system is based on the concept of role. The role of an object depends, in large part, on its aliasing relationships with other objects, with the role of each object changing as its aliasing relationships change. In this way roles capture object and data structure properties such as unique references, membership of objects in data structures, disjointness of data structures, absence of representation exposure, bidirectional associations, treeness, and absence or presence of cycles in the heap. Roles generalize linear types by allowing multiple aliases of heap objects that participate in recursive data structures. Unlike graph grammars and graph types, roles contain sufficiently general constraints to conservatively approximate any data structure. We give a semantics for mutually recursive role definitions and derive properties

. One typically defines a read-only method as a method that does not perform any write operations; however, with respect to a multi-threaded program, we augment this interpretation and let a read-only method be one that does not write to a memory location visible to more than one thread. Such a method can execute concurrently with other read-only methods. With the relaxation of mutual exclusion in mind, we present a read-write analysis that employs the ideas of shape analysis and escape analysis to identify readonly methods in Java. Approximately 31% of the methods in the JDK 1.2 core libraries meets this definition of read-only---nearly 50% more than those that do not perform any write operations. 1