6. Non-atomic Execution

Abstract

The idealization that assignments execute atomically is quite common in the literature on program verification as well as in the theoretical literature on flow analysis of parallel programs. However, in a multi-processor environment where a number of concurrently executing processors share a common memory this assumption is hardly realistic. In such an environment two threads of control may well interfere while each of them is in the process of executing an assignment. The reason is that assignments are broken into smaller instructions before execution.