Research On Load Balance Of Astronomical Image Mosaicking Grid Service

Grid Computing implements resource sharing and coordinated problem solving in dynamic, multi-institutional virtual organizations. Load balance tries to balance the load of every computer node. Divisible load theory(DLT) is a methodology that implements load balance in data-intense parallel and distributed system scheduling. The paper uses the DLT to solve the task allocation and reallocation problem of astronomical image mosaicking grid service.Firstly, the system architecture of the grid service is designed. Four workflows are analysed and summarized. The service flow of the grid service is put forward.Secondly, the task allocation of the grid service is discussed. By making a deep research into the grid task scheduler based on the ant algorithm, the author brings forward a simple and effective performance prediction method based on the ant algorithm to support the load balance. Root submitting twice adding, root submitting once adding, root computing twice adding and root computing once adding divisible task models are proposed. To tackle the storage constraint and divisible granularity problems, a faster and wider used storage constraint allocation algorithm than IBS and increasing one heap sort optimum integer approximation algorithm based on a suboptimum integer approximation algorithm are designed. The task allocation flow based forenamed models and algorithms is found. A simulaton for choosing the parameters of the performance prediction method based on the ant algorithm is done.Finally, the task reallocation of the grid service is discussed. CPU queue length, disk request queue length and task progress rate are chosen to weigh the resource performance. A load cluster method based on connected subgraph is proposed to decide whether task migration is needed and the sender and receivers of it. By analysing the change of the complete time after the task migration, the author derives a task reallocation divisible task model. A task reallocation algorithm of the grid service is designed.The task allocation and reallocation models and algorithms of astronomical image mosaicking grid service are researched and designed. A integrated solution that can get the optimum allocation of the load balance of the grid service in polynomial time is presented to improve the grid system performance.