Lock-free Concurrent Data Structures

Concurrent data structures are the data sharing side of parallel programming. Data structures give the means to the program to store data, but also provide operations to the program to access and manipulate these data. These operations are implemented through algorithms that have to be efficient. In the sequential setting, data structures are crucially important for the performance of the respective computation. In the parallel programming setting, their importance becomes more crucial because of the increased use of data and resource sharing for utilizing parallelism. The first and main goal of this chapter is to provide a sufficient background and intuition to help the interested reader to navigate in the complex research area of lock-free data structures. The second goal is to offer the programmer familiarity to the subject that will allow her to use truly concurrent methods.Comment: To appear in "Programming Multi-core and Many-core Computing Systems", eds. S. Pllana and F. Xhafa, Wiley Series on Parallel and Distributed Computin

A horizontally-scalable multiprocessing platform based on Node.js

This paper presents a scalable web-based platform called Node Scala which allows to split and handle requests on a parallel distributed system according to pre-defined use cases. We applied this platform to a client application that visualizes climate data stored in a NoSQL database MongoDB. The design of Node Scala leads to efficient usage of available computing resources in addition to allowing the system to scale simply by adding new workers. Performance evaluation of Node Scala demonstrated a gain of up to 74 % compared to the state-of-the-art techniques.Comment: 8 pages, 7 figures. Accepted for publication as a conference paper for the 13th IEEE International Symposium on Parallel and Distributed Processing with Applications (IEEE ISPA-15

A study of event traffic during the shared manipulation of objects within a collaborative virtual environment

Event management must balance consistency and responsiveness above the requirements of shared object interaction within a Collaborative Virtual Environment (CVE) system. An understanding of the event traffic during collaborative tasks helps in the design of all aspects of a CVE system. The application, user activity, the display interface, and the network resources, all play a part in determining the characteristics of event management. Linked cubic displays lend themselves well to supporting natural social human communication between remote users. To allow users to communicate naturally and subconsciously, continuous and detailed tracking is necessary. This, however, is hard to balance with the real-time consistency constraints of general shared object interaction. This paper aims to explain these issues through a detailed examination of event traffic produced by a typical CVE, using both immersive and desktop displays, while supporting a variety of collaborative activities. We analyze event traffic during a highly collaborative task requiring various forms of shared object manipulation, including the concurrent manipulation of a shared object. Event sources are categorized and the influence of the form of object sharing as well as the display device interface are detailed. With the presented findings the paper wishes to aid the design of future systems