CSR: Small: A Framework for Advanced Concurrency Debugging

本文主要研究并行软件中可能发生的并发错误的捕获问题，重点研究了四种常见的并发错误：第一种是原子性违反，即程序员没有将所有应该原子地进行的内存访问包含在同一个临界区中。结果，在执行过程中，这样的访问会与另一个线程的访问交错，导致程序状态不一致。第二种类型是过同步--这是一种缺陷，意味着存在冗余的同步操作，或者同步操作执行的粒度太粗。第三种是命令违规？当来自不同线程的内存访问之间存在正确的顺序时，这些会发生，并且在执行中，这种顺序被翻转，通常是由于没有使用正确的同步形式。当一个线程访问临界区内的共享变量并进行适当的同步时发生的错误。然而，第二个线程并发地访问相同的共享变量而不同步，并使状态不一致。该项目采取的方法涉及描述这些错误并提出检测和修复它们的技术。并行程序设计的实现是一个巨大的研究挑战，对我们的计算机工业继续取得进步的能力至关重要。伊利诺伊大学是并行计算的领导者，该提案的成果将用于增强并行计算课程。此外，该项目将涉及与英特尔的密切合作，并为学生提供在英特尔实习的机会。

This work addresses the capture of concurrency bugs that can occur in parallel software, focusing on four types of concurrency bugs that are frequent, have received little attention, and are hard to fix.The first type is atomicity violations -- bugs that occurs when the programmer fails to enclose in the same critical section all of the memory accesses that should occur atomically. As a result, during execution, such accesses get interleaved with accesses from another thread that make the program state inconsistent.The second type is over-synchronization -- a defect that implies that there are redundant synchronization operations or that the synchronization operations are performed at a grain that is too coarse. As a result, the program's performance is poor.The third type is ordering violations ? these occur when there is a correct order between memory accesses from different threads and, in an execution, such order is flipped, usually due to not using the correct form of synchronization.The final type is asymmetric data races ? bugs that occur when a thread accesses shared variables inside a critical section with appropriate synchronization. However, a second thread concurrently accesses the same shared variables without synchronization, and makes the state inconsistent.The approach taken by this project involves characterizing these bugs and proposing techniques to detect and fix them. A deliverable of this work is a unified framework for bug detection.The realization of parallel programming is a Grand Research Challenge and is crucial to our computer industry's ability to continue to make progress. The University of Illinois is a leader in parallel computing and the outcomes of this proposal will be used to enhance courses on parallel computing. In addition, this project will involve close collaboration with Intel and provide students with the opportunity to engage in internships at Intel.