Exclusion for composite objects

Designing concurrent object-oriented programs is hard. Correct programs mus t coordinate multiple threads accessing composite objects, using low-level mechanisms such as locks and read-write sets. Efficient programs must balan ce the complexity and overhead of the coordination mechanisms against the i ncreased performance possible through concurrency. A method-level algebra o f exclusion provides a succinct description of the conditions under which a thread must be excluded from a component of a composite object. Using the algebra, programmers can check whether their programs meet their exclusion requirements, can eliminate redundant exclusion controls, and can remove sy nchronisation overhead by reducing concurrency.