Analysis of communicating processes for non-progress

Abstract

The problem of testing two processes (specified as finite-state machines) communicating asynchronously with each other using send and receive commands over a set of message types is considered for two forms of nonprogress: deadlock and unspecified reception. Since the nonprogress problem is undecidable, a dataflow approach is used to obtain sufficient conditions under which the two processes are free of deadlock and unspecified reception. The approximation analysis is based on weakening the receive operation. Polynomial time algorithms are presented to perform the analysis. This problem arises in the context of dataflow analysis of the processes that communicate by message passing and in the context of showing correctness of protocol specifications. Diagrams are provided for some networks that can be certified to be free of unspecified receptions using the algorithms. The problem of testing for deadlock in more than two processes still remains open.<>