CRI: A Computational Infrastructure for Experimentation on Relaxed Concurrency Abstractions and their Applications

该项目采购了一个由多核处理器引擎构建的共享内存并行机器组成的小型集群，旨在探索在保留程序语义的同时通过放松约束来增加并发性和减少开销的方法。这项工作-探索了并发和并行编程的新方法，-激发了新的松散同步并行算法类，并推动了具有实际应用的编程范例的未来发展。该项目汇集了编译器设计和编程语言、运行时环境、并行算法和应用程序方面的研究人员。通过在实际应用程序的上下文中探索最先进的编程原则和概念，并激发能够容忍数据访问延迟的巨大差异的新算法类，该基础设施创造了新的协同作用。使用Java或c#这样的语言高效安全地编写并发程序的问题，即使在现有的单处理器平台上也是如此，但当执行平台支持真正的并行性时（例如，在基于最近开发的多核处理器设计的并行系统上），问题就变得更加严重了。这项工作着眼于允许在并发程序中过度指定的安全不变量在不危及不变量时自动和动态地放松的技术。这项调查利用了基于事务的并发控制和安全推测执行方面的工作，这些工作允许对代码的共享区域进行逻辑并发访问，但要确保此类访问不会违反预期的序列化不变量。该项目在编程语言上下文中研究了不同的事务和推测模型，探讨了这些模型在安全性和性能方面的权衡，并研究了在提议的多集群平台上开发的抽象的可扩展性特征。更广泛的影响：这项工作导致了对并发程序构造的更好理解，并因此改进了实现。该项目支持各种教育相关活动，包括课堂教学和讲习班。解决许多新兴应用需求的基础技术，该项目还与行业互动，并有助于培养研究生。将通过研讨会吸引少数民族学生。

This project, procuring a small cluster of shared-memory parallel machines built with multicore processor engines, aims at exploring approaches to increase concurrency and reduce overheads by relaxing constraints while preserving program semantics. The work -Explores novel approaches to concurrent and parallel programming,-Motivates new classes of loosely synchronous parallel algorithms, and-Spurs future developments in programming paradigms with real applications.The project brings together researchers in compiler design and programming languages, runtime environments, and parallel algorithms and applications. The infrastructure creates new synergies by exploring state-of-the-art programming principles and concepts in the context of real applications and motivating novel algorithmic classes capable of tolerating large discrepancies in data access latencies.The problems of writing concurrent programs effectively and safely in languages like Java or C#, which provide integral support for multithreading, even on existing single processor platforms, become exacerbated when the execution platform supports true parallelism (e.g., on parallel system based on recently developed multi-core processor designs). This work looks at techniques that permit overspecified safety invariants in concurrent programs to be relaxed automatically and dynamically whenever the invariants are not compromised. This investigation leverages work on transaction-based concurrency control and safe speculative execution that permit logically concurrent access to shared regions of code, but which ensure that such accesses do not violate intended serialization invariants. The project studies different transactional and speculative models in a programming language context, explores tradeoffs among these models with respect to safety and performance, and investigates the scalability characteristics of the abstractions developed on the proposed multicluster platform.Broader Impact: The work leads to a better understanding of concurrent program construction, and consequently, improved implementations. The project supports a variety of educational related activities, including classroom instruction and workshops. Addressing foundational technologies for many emerging application needs, the project also interacts with industry and contributes to train graduate students. Minority students will be attracted using seminars.