HLA时间管理中的死锁问题研究

研究高层体系结构中的死锁问题对于正确理解HLA标准中的时间推进机制、设计运行支撑平台RTI软件中的时间推进服务、以及开发基于逻辑时间的HLA/RTI仿真应用等都具有重要的意义.论文从零前瞻值、时间推进服务、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.论文揭示了一个带有相当普遍性的原理,即"水平面原理".该原理表明:当死锁发生时,所有程序都无法向前推进而处于相对静止状态,犹如平静的水面一样.在HLA/RTI仿真中表现为处于死锁状态的所有程序具有相同最大可用逻辑时间,此时所有程序均无法继续向前推进.

Research on Deadlock in the HLA Time Management

It is rather important to study deadlocks in the High Level Architecture(HLA) for correctly comprehending time advancing mechanism in HLA standards,designing time management services in Runtime Infrastructure(RTI),and developing HLA/RTI simulations based on logical time.This paper investigates deadlocks in the HLA time management from different aspects,including deadlocks resulted from zero lookahead,from time advance services,and from time management algorithms as well as the resolution of deadlocks.A series of interesting phenomena are also explored,and varieties of cases in which deadlocks must happen or must not happen are also demonstrated.Particularly,the paper brings forward a rather common principle called Water Surface Rule.This rule shows that all programs cannot advance further and all of them are in relatively quiet status when deadlock occurs,which seems to be the calm water surface.In HLA/RTI simulations,all programs in deadlock status have the identical Greatest Available Logical Time(GALT) so that none of them can advance logical time any further.