一致性算法探寻（扩展版）13

11 Conclusion

Algorithms are often designed with correctness, efficiency, and/or conciseness as the primary goals. Although these are all worthy goals, we believe that understandability is just as important. None of the other goals can be achieved until developers render the algorithm into a practical implementation, which will inevitably deviate from and expand upon the published form. Unless developers have a deep understanding of the algorithm and can create intuitions about it, it will be difficult for them to retain its desirable properties in their implementation.

In this paper we addressed the issue of distributed consensus, where a widely accepted but impenetrable  algorithm, Paxos, has challenged students and developers for many years. We developed a new algorithm, Raft, which we have shown to be more understandable than Paxos. We also believe that Raft provides a better foundation for system building. Using understandability as the primary design goal changed the way we approached the design of Raft; as the design progressed we found ourselves reusing a few techniques repeatedly, such as decomposing the problem and simplifying the state space. These techniques not only improved the understandability of Raft but also made it easier to convince ourselves of its correctness.

11 结论

算法通常以正确性、有效性、和/或简明扼要作为设计的主要目标。尽管这些都是有价值的目标，我们仍然相信易懂性也同样重要。只有开发者将算法渲染到实际实现中才有可能实现这些目标，这必将偏离和扩展本文。除非程序员可以很好的理解算法，并拥有创造它的直觉，不然对他们来说在他们的实现中保持理想的属性仍然是个难题。

本文中，我们讨论了分布式一致性问题，一个广泛被接收但令人费解的算法——Paxos，多年来一直在挑战学生和开发者。我们开发了一个新的算法——Raft，我们已经展示了它比Paxos更易懂。我们还认为Raft提供了一个很好的系统构建的基础。伴着易懂性为主目标让我们开始了Raft的设计；随着设计的进展，我们发现我们在使用一些重复的技巧，比如分解问题和简化状态空间。这些技巧不仅提高了Raft的易懂性，也更容易让我们相信它的正确性。

12 Acknowledgments

The user study would not have been possible without the support of Ali Ghodsi, David Mazi`eres, and the students of CS 294-91 at Berkeley and CS 240 at Stanford. Scott Klemmer helped us design the user study, and Nelson Ray advised us on statistical analysis. The Paxos slides for the user study borrowed heavily from a slide deck originally created by Lorenzo Alvisi. Special thanks go to David Mazi`eres and Ezra Hoch for finding subtle bugs in Raft. Many people provided helpful feedback on the paper and user study materials, including Ed Bugnion, Michael Chan, Hugues Evrard, Daniel Giffin, Arjun Gopalan, Jon Howell, Vimalkumar Jeyakumar, Ankita Kejriwal, Aleksandar Kracun, Amit Levy, Joel Martin, Satoshi Matsushita, Oleg Pesok, David Ramos, Robbert van Renesse, Mendel Rosenblum, Nicolas Schiper, Deian Stefan, Andrew Stone, Ryan Stutsman, David Terei, Stephen Yang, Matei Zaharia, 24 anonymous conference reviewers (with duplicates), and especially our shepherd Eddie Kohler. Werner Vogels tweeted a link to an earlier draft, which gave Raft significant exposure. This work was supported by the Gigascale Systems Research Center and the Multiscale Systems Center, two of six research centers funded under the Focus Center Research Program, a Semiconductor Research Corporation program, by STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA, by the National Science Foundation under Grant No. 0963859, and by grants from Facebook, Google, Mellanox, NEC, NetApp, SAP, and Samsung. Diego Ongaro is supported by The Junglee Corporation Stanford Graduate Fellowship.

12 致谢

本章是作者的致谢，不考虑翻译了

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