Process Migration Technology Implementation And Application In Multi-machine Environment

With the development of the computer technology, the performance of computer systems are continuously improved, but the price are declining, the distributed systems have more and more advantages in cost performance and expansibility. In addition, the demand for high performance computing makes the using of cluster to be more widely. How to effectively use computing resources of clusters, keep the load balance, ensuring the performance of computing tasks, need to use process migration technology.Especially, in the cluster based on personal workstations, workstations are not exclusive, and they may be heterogeneous. When the user needs withdraw the private resources or the system is load unbalanced, the task should be moved to another node, and continue running. It is much better that the implementation of process migrating is platform-independent.This thesis mainly discusses the process migration for multi-machine environment, and applies it to image processing field. Traditional process migration systems usually rely on special software or hardware environment, according to the characteristic of ordinary multi-motor environment, we use Java platform to implement process migrating. This meets the cross-platform requirements.Process migrating do not only migrate source codes, but also migrates state information of the process in a checkpoint. The core of the process migration technology is how to capture and restore process state data. According to the characteristic of Java system structure, this thesis adopts the process migration technology based on JPDA and bytecode. The process information is captured by using the method based on JPDA. The restoring phase is a difficult point of this thesis. The user program should jump to the breakpoint and then continue to run after the process Is rebuilt, but some codes, such as declaration statement, could not be skipped. Using JPDA can only access and modify data, it cannot declare new object and change program process. So we use bytecode modification technology to solve these problems.In addition, this thesis adopts checkpoint mechanism to save and transmit process related information. First, we design several special classes to store external data of process (e.g., source code) and process state information. Second, we adopt the checkpoint control strategy based on time, because the occurring time of the process migrating is uncertain, and combine the characteristic of multi-machine environment. The checkpoint is enabled dynamically, and then the process information is captured.The process migration based on JPDA and bytecode in this thesis is proved practicable by using a validation program. Finally, a prototype system named 'JMigrate' is developed. And the thesis described performance test and usability analysis in image processing. And tests show that the system has good performance and high usability in image processing.