CSR: Small: Nested Distributed Software Transactional Memory: Protocols, Mechanisms, and Java Package

在这个项目中，开发了嵌套分布式事务存储器(TM)的协议、机制和Java实现。分布式TM承诺缓解基于锁的分布式并发控制的可编程性、可伸缩性和性能挑战。新兴的分布式TM实现导出了一个简单的编程接口，该接口排除了锁，并产生了与基于锁的分布式并发控制相当或更好的性能。嵌套对于分布式TM在可组合性、功能性、故障管理和性能方面是必不可少的。该项目正在开发协议和机制，以支持分布式TM中的封闭和开放嵌套。关闭嵌套允许在不中止父事务的情况下中止嵌套事务，但反之亦然。开放嵌套允许在不中止嵌套事务的情况下中止父事务，反之亦然，从而允许更大的并发性。为了支持这些嵌套模型，该项目正在开发分布式事务冲突解决协议、分布式缓存一致性协议，以及用于透明地执行补偿事务以消除已提交事务的影响的机制。该项目正在开源的HyFlow分布式TM Java包(hyflow.org)中实现这些技术。该项目还将这项技术(技术和HyFlow实现)过渡到美国海军的宙斯盾战斗系统，该系统使用分布式并发控制。此外，该项目的成果正在被纳入弗吉尼亚理工大学的高级研究生课程，其中包括弗吉尼亚州布莱克斯堡的学生、弗吉尼亚州达尔格伦分部(NSWCDD)的美国海军水面作战中心达尔格伦分部(NSWCDD)的科学家和工程师(通过弗吉尼亚理工大学在NSWCDD的研究生拓展计划)，以及通过弗吉尼亚理工大学在埃及的VT-MENA计划在中东和北非的学生。

In this project, protocols, mechanisms, and a Java implementation of nested distributed transactional memory (TM) are developed. Distributed TM promises to alleviate the programmability, scalability, and performance challenges of lock-based distributed concurrency control. Emerging distributed TM implementations export a simple programming interface that precludes locks and are yielding performance comparable to, or better than lock-based distributed concurrency control. Nesting is essential to distributed TM for composability, functionality, fault-management, and performance. The project is developing protocols and mechanisms to support closed and open nesting in distributed TM. Closed nesting allows a nested transaction to be aborted without aborting the parent transaction, but not vice versa. Open nesting allows a parent transaction to be aborted without aborting the nested transaction, and vice versa, permitting greater concurrency. To support these nesting models, the project is developing distributed transactional conflict resolution protocols, distributed cache coherence protocols, and mechanisms for transparently executing compensating transactions to undo the effects of committed transactions. The project is implementing these techniques in the open-source, HyFlow distributed TM Java package (hyflow.org). The project is also transitioning this technology (techniques and HyFlow implementation) to US Navy's Aegis Combat System, which uses distributed concurrency control. Additionally, the project's results are being incorporated into advanced graduate courses at Virginia Tech that includes students at Blacksburg, VA, scientists and engineers at US Naval Surface Warfare Center Dahlgren Division (NSWCDD), VA (through Virginia Tech's graduate outreach program at NSWCDD), and students in the Middle East and North Africa through Virginia Tech's VT-MENA program at Egypt.