Joshua B. Leners

Yesquel: scalable sql storage for web applications

Web applications have been shifting their storage systems from sql to nosql systems. nosql systems scale well but drop many convenient sql features, such as joins, secondary indexes, and/or transactions. We design, develop, and evaluate Yesquel, a system that provides performance and scalability comparable to nosql with all the features of a sql relational system. Yesquel has a new architecture and a new distributed data structure, called YDBT, which Yesquel uses for storage, and which performs well under contention by many concurrent clients. We evaluate Yesquel and find that Yesquel performs almost as well as Redis---a popular nosql system---and much better than mysql Cluster, while handling sql queries at scale.

It's on me! the benefit of altruism in BAR environment

Cooperation, a necessity for any peer-to-peer (P2P) cooperative service, is often achieved by rewarding good behavior now with the promise of future benefits. However, in most cases, interactions with a particular peer or the service itself eventually end, resulting in some last exchange in which departing participants have no incentive to contribute. Without cooperation in the last round, cooperation in any prior round may be unachievable. In this paper, we propose leveraging altruistic participants that simply follow the protocol as given. We show that altruism is a simple, necessary, and sufficient way to incentivize cooperation in a realistic model of a cooperative services last exchange, in which participants may be Byzantine, altruistic, or rational and network loss is explicitly considered. By focusing on network-level incentives in the last exchange, we believe our approach can be used as the cornerstone for incentivizing cooperation in any cooperative service.

Taming uncertainty in distributed systems with help from the network

Network and process failures cause complexity in distributed applications. When a remote process does not respond, the application cannot tell if the process or network have failed, or if they are just slow. Without this information, applications can lose availability or correctness. To address this problem, we propose Albatross, a service that quickly reports to applications the current status of a remote process---whether it is working and reachable, or not. Albatross is targeted at data centers equipped with software defined networks (SDNs), allowing it to discover and enforce network partitions: Albatross borrows the old observation that it can be better to cause a problem than to live with uncertainty, and applies this idea to networks. When enforcing partitions, Albatross avoids disruption by disconnecting only individual processes (not entire hosts), and by allowing them to reconnect if the application chooses. We show that, under Albatross, distributed applications can bypass the complexity caused by network failures and that they become more available.