关键词: 分布式工作流, 自适应调度, 比例—积分—微分控制, 关键路径

Abstract: To improve the scheduling efficiency of real-time tasks in a distributed workflow systems, an Adaptive Scheduling Method(ASM) based on Proportional-Integral- Derivative (PID) control was proposed. ASM adopted an assigning strategy based on dynamic critical paths to assign tasks to different process engines. Then, tasks in each engine were scheduled by a feedback strategy, which tuned parameters of a real-time tasks by elastic scheduling algorithm according to the output of admission controller and PID controller so as to maximize the processing capacity of the engine. Besides, to avoid instantaneous overloads, ASM adopted an admission control strategy, which controlled the number of tasks entering the system according to the current load of the system in order to ensure the stability of the system.

Key words: distributed workflow, adaptive scheduling, proportional-integral-derivative control, critical path