Mikael Högqvist

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A lease is a token which grants its owner exclusive access to a resource for a defined span of time. In order to be able to tolerate failures, leases need to be coordinated by distributed processes. We present FaTLease, an algorithm for fault-tolerant lease negotiation in distributed systems. It is built on the Paxos algorithm for distributed consensus, but(More)
—Large-scale distributed systems often require scal-able and fault-tolerant mechanisms to coordinate exclusive access to shared resources such as files, replicas or the primary role. The best known algorithms to implement distributed mutual exclusion with leases, such as Multipaxos, are complex, difficult to implement, and rely on stable storage to persist(More)
Time series analysis, as an application for high dimensional data mining, is a common task in biochemistry, meteorology, climate research, bio-medicine or marketing. Similarity search in data with increasing dimensionality results in an exponential growth of the search space, referred to as Curse of Dimensionality. A common approach to postpone this effect(More)
In this work, we present a distributed caching solution which addresses the problem of efficient delivery of HTTP live streams in large private networks. With our system, we have conducted tests on a number of pilot deployments. The largest of them, with 3000 concurrent viewers, consistently showed that our system saves more than 90% of traffic towards the(More)
Peer-to-peer (P2P) technology has long been considered a natural complement to standard CDN infrastructure for video distribution since it greatly reduces costs and improves quality of user experience. However, P2P solutions have traditionally required the installation of additional software or plugins to be deployed, which significantly hinders adoption.(More)
A file system snapshot is a stable image of all files and directories in a well-defined state. Local file systems offer point-in-time consistency of snapshots, which guarantees that all files are frozen in a state in which they were at the same point in time. However, this cannot be achieved in a distributed file system without global clocks or synchronous(More)