Modeling And Analysis Of Few Concurrent Problems Based On Petri Nets

Petri nets can not only use visual graphic description, but also can be supported by formal mathematical methods, it is a kind of formalized, graphical distributed system modeling and analysis tools. It can analyze system static characteristics accurately and analyze system dynamic behavior well, thereby good depicting system dynamic behavior and analyzing system performance. It may adopt formalized visual graphics and introduce many mathematical methods to analyze and verify its properties.At present, most software systems are concurrence systems, it is a parameter standard which can be used to measure operation efficiency of system. In order to achieve the effect with"little effort do much work", the system environments available are requiring concurrent increasingly, only in this way can we use system resources environment and can we make a system has stronger competitiveness. As an excellent formalism description and analysis tools, Petri nets can describes and analyzes this kind system easily. The adoption of formal software technology, not only benefits to the intercommunion of developers and promotes the software robustness, but also reduce the total development time and decrease great number of errors in the early design phase.The main work of this paper is as follows:(1) Analysis of the Dining Philosophers problems based on Petri Nets. The Dining Philosophers problem is a classical example of synchronization and concurrency of describing the shared resources. The live and starvation-free are the prerequisites to solve this problem, and efficiency is basic requirements. Since the competition of resources that philosophers cannot simultaneously in eating state. Considering fairness of philosophers, we define concept of delayed Petri nets. Solved the conflict caused by competition of resources and improving the efficiency.(2) Modeling and improving Petri net model of the Sender-Receiver problem. Solving the user require to communicate and required user is free, while the channels are busy, several users request to communicate with other several users simultaneously, while the other several users are communicating, considering the channel utilization and the conflict of shared resources, we use the stack technology to analyze and verify, bring forward a model which is stronger and wider application of Petri nets.