Block-based Atomicity in Message-passing Distributed Programs

In this paper, we have studied the notion of atomicity in message-passing distributed programs. The difference between the notion of atomicity in shared memory programs and messagepassing programs has been discussed in detail. Due to the nature of communication in messagepassing programs, the atomicity requirement in shared memory programs (serializability) does not guarantee the same level of atomicity in message-passing programs. We have referred to the atomicity level guaranteed by the serializability requirement in message-passing programs as the weak atomicity. We have defined the requirements that guarantee a level of atomicity in message-passing programs similar to that in shared memory programs. We have referred to it as the strong atomicity requirement. Both of weak and strong atomicity have been formally defined. The notion of atomicity can be employed to significantly reduce the state space to be considered in verification. Moreover, atomicity violations in a run typically indicate the presence of program bugs. Consequently, the concepts presented in this paper can be exploited to reduce the cost of the verification of message-passing distributed programs.