In the past researchers have developed specialized programs to aid programmers detecting concurrent programming errors such as deadlocks, livelocks, starvation and data races. In this work we propose a language extension to the aspect-oriented programming language AspectJ, in the form of three new pointcuts, lock(), unlock() and maybeShared(). These pointcuts allow programmers to monitor program events where locks are granted or handed back, and where values are accessed that may be shared amongst multiple Java threads. We decide thread-locality using a static thread-local-objects analysis developed by others. Using the three new primitive pointcuts, researchers can directly implement efficient monitoring algorithms to detect concurrent-programming errors online. As an example, we describe a new algorithm which we call RACER, an adaption of the well-known ERASER algorithm to the memory model of Java. We implemented the new pointcuts as an extension to the AspectBench Compiler, implemented the RACER algorithm using this language extension and then applied the algorithm to the NASA K9 Rover Executive and two smaller programs. Our experiments demonstrate that our implementation is effective in finding subtle data races. In the Rover Executive RACER finds 12 data races, with no false warnings. Only one of these races was previously known.

With aspect-oriented programming, changes can be treated explicitly and directly at the programming language level. An approach to aspect-oriented change realization based on a two-level change type model is presented in this paper. In this approach, aspect-oriented change realizations are mainly based on aspect-oriented design patterns or themselves constitute pattern-like forms in connection to which domain independent change types can be identified. However, it is more convenient to plan changes in a domain specific manner. Domain specific change types can be seen as subtypes of generally applicable change types. These relationships can be maintained in a form of a catalog. Some changes can actually affect existing aspect-oriented change realizations, which can be solved by adapting the existing change implementation or by implementing an aspect-oriented change realization of the existing change without having to modify its source code. As demonstrated partially by the approach evaluation, the problem of change interaction may be avoided to a large extent by using appropriate aspect-oriented development tools, but for a large number of changes, dependencies between them have to be tracked. Constructing partial feature models in which changes are represented by variable features is sufficient to discover indirect change dependencies that may lead to change interaction. 1.