Software Fault-Tolerance based on Observation and Control of Distributed Programs

为了降低软件故障带来的风险，研究了一种基于前瞻控制执行的容错方法。 在这种方法中，程序以前瞻模式运行，而不影响外部环境。在前瞻期间，跟踪足够的信息，以便可以分析故障。 如果对执行的分析显示没有错误，则提交前瞻执行，并且其效果对环境可见。 否则，丢弃来自先行执行的结果，并且系统以受控模式运行。在这种模式下，系统通过引入额外的同步或改变消息的顺序来进行控制，以避免在lookahead期间发生的错误，该项目有三个主要组成部分-用于检测软件故障的算法，用于自动控制的算法，如控制消息的插入和基于lookahead的消息的重新排序，以及支持lookahead的受控扩展的系统。 在软件故障检测方面，本文将对已有的算法进行扩展，使其适用于更一般的故障计算模型。对于自动控制，该项目将重点关注并发程序中的同步错误。最后，将开发一个支持带前瞻的受控扩展的Java系统。

To reduce the risks associated with software faults, the research focuses on a fault tolerance method based on controlled execution with lookahead. In this approach, a program is run in a lookahead mode without affecting the external environment. During lookahead, sufficient information is traced so that it can be analyzed for faults. If the analysis of the execution shows that there are no faults, then the lookahead execution is committed and its effects are visible to the environment. Otherwise, the results from the lookahead execution are discarded, and the system is run in a controlled mode. In this mode, the system exercises control by introducing additional synchronization or by changing the order of messages to avoid the fault that occurred during lookahead.There are three main components of the project - algorithms fordetection of software faults, algorithms for automaticcontrol such as insertion of control messages and reordering ofmessages based on lookahead, and a system which supports controlledexecution with lookahead. For detection of software faults, previous algorithms will be extended to work for more general model ofcomputation in the presence of failures. For automatic control, the project will focus on synchronization faults in concurrent programs.Finally, a system in Java that supports controlledexecution with lookahead will be developed.