CNS Core: Small: Modernizing Consistency Models

该项目通过探索使大规模计算机应用程序更容易正确编程和更快运行的新方法来促进科学进步。这样的应用程序是由几个部分构建的，其中一个关键部分是分布式数据存储，它调解对应用程序数据的访问。该项目探索了新的方法来指定应用程序和数据存储之间的接口，以便应用程序可以更快地完成对数据存储的所有访问。它还探讨了应用程序如何使用这种新的，更快的接口，而不会使编程变得更加复杂。总之，这应该通过引入新的接口（一致性模型），展示这些新接口不会增加编程复杂性，开发支持新接口的新数据存储，以及演示新接口和系统如何导致更快的应用程序来推进分布式系统领域。这些改进有可能提高大规模计算机应用程序的速度和正确性，这些应用程序是我们生活中不可或缺的一部分。此外，本发明还这个项目将通过本科生和研究生的参与来促进发现和扩大科学的参与。一致性模型定义了分布式系统和建立在其上的应用程序之间的契约。主要的一致性模型是几十年前定义的，并假设应用程序执行的限制性模型，排除了多分派的使用-应用程序执行和系统之间的多个并发操作-和分布式执行-应用程序处理同时在多个地方发生。然而，多分派和分布式执行在现代应用程序中很常见，因为与经典模型假设的单分派和集中式执行相比，它们大大减少了延迟。该提案旨在通过包括多分派通信和分布式执行来实现一致性模型的现代化。这将允许程序员严格推理其应用程序的正确性，同时还获得多分派和/或分布式执行的延迟优势。此外，它试图将现代一致性模型定义为等同于经典模型：如果应用程序在经典模型上运行时是正确的，同时尊重其假设，那么在现代化模型上运行时也是正确的。这避免了新的一致性模型的保证和性能之间的典型微妙的权衡，并完全隐藏了程序员对系统的并发访问。相反，它允许程序员坚持对他们已经知道的经典一致性模型进行推理。对于每一个多分派，然后分布式执行，我们建议定义新的一致性模型，设计系统，提供新的一致性模型，然后通过评估证明端到端的延迟改进的应用程序建立在新的系统上。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

This project promotes the progress of science by exploring new methods for making large-scale computer applications easier to program correctly and run faster. Such applications are built out of several pieces with one key piece being a distributed data store that mediates access to the application's data. This project explores new ways to specify the interface between applications and the data store so that applications can complete all their accesses to the data store more quickly. It also explores how applications can use this new, faster interface without making programming more complicated. Together, this should advance the field of distributed systems by introducing new interfaces (consistency models), showing these new interfaces do not add programming complexity, developing new data stores that support the new interfaces, and demonstrating how the new interfaces and systems result in faster applications. These improvements have the potential to improve the speed and correctness of the large-scale computer applications that are an integral part of our lives. Further, this project will advance discovery and broaden participation in science by involving undergraduate and graduate researchers.Consistency models define the contract between a distributed system and the applications built on it. The dominant consistency models were defined decades ago and assume restrictive models of application execution that preclude the use of multi-dispatch---multiple concurrent operations between an application execution and the system---and distributed execution---application processing happening in multiple places simultaneously. Multi-dispatch and distributed execution, however, are common in modern applications because they greatly reduce latency compared to the single-dispatch and centralized execution assumed by classic models. This proposal seeks to modernize consistency models by including multi-dispatch communication and distributed execution. This will allow programmers to rigorously reason about the correctness of their applications while also gaining the latency benefit of multi-dispatch and/or distributed execution. Further, it seeks to define modern consistency models to be equivalent to classic models: if an application is correct when running on a classic model while respecting its assumptions, it will be correct when run on the modernized model. This avoids the typical subtle trade-offs between guarantees and performance of new consistency models and fully hides the concurrent access to the system from programmers. Instead, it allows programmers to stick to reasoning about the classic consistency models they already know. For each of multi-dispatch and then distributed execution, we propose defining new consistency models, designing systems that provide the new consistency models, and then demonstrating end-to-end latency improvement for applications built on the new systems through evaluation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.