HLA时间管理中死锁的研究

Research on Deadlock in HLA Time Management

时间管理服务是高层体系结构HLA(High Level Architecture)的重要组成部分,而考虑不全面的时间推进机制和算法会导致死锁,进而导致整个仿真系统无法向前推进。从零前瞻量、时间管理策略、时间管理算法以及死锁的解除等方面对分布式仿真中的死锁问题进行了多方面的研究,探讨了死锁发生时系统所具有的一系列现象,论证了发生死锁和不可能发生死锁时的各类情形.讨论了死锁出现的原因,对Frederick算法及身高测量法存在的不足之处进行了修正,提出了一种严格序算法,并证明了这种方法不会产生死锁现象。在设计一个联邦时可考虑使盟员灵活地使用保守和乐观两种时间推进机制,并在对保守盟员计算GALT时使用序算法,这样就可以在仿真过程中有效地避免死锁的产生。

Time management is an important component of High Level Architecture,while inconsiderate time advance mechanism and unreasonable algorithm can result in a deadlock so that the whole federation can not be able to advance anymore.The deadlock in the HLA time management was investigated from different aspects,including deadlocks resulted from zero look-ahead,from time management strategy,and from time management algorithms as well as there solution of deadlocks.A series of interesting phenomena were explored,and varieties of cases in which deadlocks would or not happen were demonstrated.The reason of appearing deadlock was analyzed,the shortcoming resulted in the Frederick algorithm and Stature-measuring algorithm was corrected,and an ordering algorithm was provided which was proved not to result in deadlock problem.Conservative and optimistic time advance mechanism should be used actively when designing a federation,and improved Strict-Ordering algorithm should be used when calculating the GALT of conservative federates.So the deadlock problem can be avoided effectively in the processing of simulation.