Research On Task Scheduling Of Distributed Measurement And Control System

With rapid development of distributed computing ,computer and network technology, distributed system formed with networks is used widely.Network measurement and control technology and new instruments that have the network function are advantageous to construct distributed measurement and control system. Distributed measurement and control system has superiority for completing complicated and remote tasks that measure and control the big scope.In distributed measurement and control system, task scheduling is a key technology, whose main content is task migration. In this paper, according to the feature of tasks in the distributed measurement and control system, task scheduling is discussed and new task scheduling methods that can promote system efficiency effectively and attain load balancing are brought up. First, under deeply study of measurement and control tasks whose every status can be foreknown in distributed measurement and control system, a static tasks matching and scheduling algorithm for distributed measurement and control system by using genetic algorithms is introduced. In distributed measurement and control system, genetic algorithm can solve effectively the NP-hard problem of implementing optimum static tasks matching and scheduling. By using the static tasks matching and scheduling algorithm of distributed measurement and control system, overall optimized search has been realized. This algorithm guarantees not only tasks correlativity but also the best scheme for tasks matching and scheduling.In this article, the relation of task granularity and system property in static tasks matching and scheduling of distributed measurement and control system is discussed. In distributed measurement and control system, the emergence and operation of the larger measurement and control tasks are not foreseeable. The status of load on each node change dynamically. This text put forward two kinds of dynamic task scheduling algorithm for distributed measurement and control system. In order to execute tasks together, the algorithms dynamically migrate tasks according to the current status of load on each node. So the algorithms can promote system efficiency and attain load balancing. In order to carry out dynamic task scheduling effectively, the method of name and orientation is provided for tasks of distributed measurement and control system. The method assigns each task a name that can identify them uniquely and orientates tasks accurately according to their name when a task was dispatched other machine. In this paper, a new class object naming (CON) method is proposed based on object-oriented method. It is a universal and position independent naming method that has realized naming and orientating tasks of distributed measurement and control system. Java is adopted to realize this method. Before implementing dynamic task scheduling algorithm for distributed measurement and control system, the status of load on each node must be obtained availably. Under thoroughly research of different characteristics of each computer in distributed measurement and control system, a new status index of load: Load= is raised. On the basis of this index, the status of load on each node is judged. The status index of load on each host is obtained and calculated by using a procedure that inspects the load. Java has a series of characteristic such as simplicity,distribution,safety,object-oriented,neutral system construction,transplant,multi-thread. In proceeding the thorough investigation of Java, this text put forward a kind of dynamic task scheduling algorithm of distributed measurement and control system. In this algorithm, task has been not only migrated from heavy load computer to light load computer but also operated on light load computer based on Object Serialization,Multi-Thread and Remote Method Invocation of Java. So this algorithm can dynamically schedules tasks according to the current status of load on each host. After analyzing the system construction of Java's safety, the Java's ability to pro...