SHF: Small: Specifying and Verifying Essential Deterministic Behavior of Concurrent Programs

并行多线程程序比顺序程序更难编写，因为在编写并行程序时，程序员除了程序的算法正确性外，还必须考虑由于线程交织而导致的所有可能行为。 一个普遍的信念是，唯一的方法，使多线程编程访问大量的程序员是拿出明确分离的推理功能的正确性，从推理额外的行为所产生的parallel.This项目研究的策略，从其功能的正确性分离的程序的并行化正确性方面的编程范式和相关的工具。首先，对于大多数并行程序，期望由并行程序中的线程调度器引入的非确定性不改变程序的预期输出。 这个项目将开发一个断言框架，用于指定并行程序的区域在不确定的线程交织的情况下仍具有确定的行为。第二个策略是基于这样的观察，即并行程序开发中的一个自然步骤是首先扩展具有受控量的非确定性的顺序算法，然后进行实际的并行化，当额外的非确定性由线程交织引入时。这个项目将研究使用非确定性顺序程序作为规范机制，这样对于并行程序的每次执行，存在相应的非确定性顺序程序的等效执行。这种非确定性顺序程序将并行化正确性与功能正确性解耦。

Parallel multi-threaded programs are more difficult to write than their sequential counterparts because while writing parallel programs programmers must consider all possible behaviors due to thread interleavings, in addition to the algorithmic correctness of the program. A widespread belief is that the only way to make multi-threaded programming accessible to a large number of programmers is to come up with programming paradigms and associated tools that explicitly separate reasoning about functional correctness from reasoning about additional behaviors arising due to parallelism.This project investigates strategies for separating the parallelization correctness aspect of a program from its functional correctness. First, for most parallel programs it is desired that the non-determinism introduced by the thread scheduler in a parallel program does not change the intended output of the program. This project will develop an assertion framework for specifying that regions of a parallel program behave deterministically despite non-deterministic thread interleaving.The second strategy is based on the observation that a natural step in the development of a parallel program is to first extend the sequential algorithm with a controlled amount of non-determinism, followed by the actual parallelization, when additional non-determinism is introduced by thread interleavings. This project will investigate the use of non-deterministic sequential programs as a specification mechanism, such that for each execution of a parallel program there exists an equivalent execution of the corresponding non-deterministic sequential program. Such non-deterministic sequential programs decouple parallelization correctness from functional correctness.