Identifying functionality of fragments in concurrent programs

Abstract

To identify the functionality of a program fragment is to determine the effect to program behavior caused by removing the fragment. When given a concurrent program with the proof of all desired properties, we are assured the correctness. Left unsaid are often the purposes of various fragments in the program text. A scenario approach to answering questions such as What is the purpose of this variable?, What is the purpose of this busy-waiting loop?, What is the purpose of this assignment?, and so forth, is proposed. By answering such questions, one gains a component-wise understanding of the program. The task of determining functionality of fragments is shown to be less demanding than the original proof of the complete program. The gain is a further understanding not provided by proofs. Several classical solutions to the n-process critical section problem are used for illustration.