Diss.--Bonn--Universität, 1999. / Bibligr. p. XI-XXI.

Th.--Roma--Pontificia universitate gregoriana, 2000. / Bibliogr. p. 377-401. Index.

Thèse de doctorat : Informatique : Université Paris-Dauphine : 2009. / bibliogr.67 ref. Index.

Thesis (M.S. in)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Matt Carlyle. Includes bibliographical references (p. 29). Also available online.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 92 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 89-92).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Java; weak reference; reference objects; distributed objects; distributed garbage collection. Includes bibliographical references (p. 91-93).

Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Neil C. Rowe, Gary L. Kreeger. Includes bibliographical references (p. 121-122). Also available online.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: java; software visualization; probes; event notification. Includes bibliographical references (p. 79-82).

This report describes StarMapper, a mobile appliation designed for the Android platform that interactively maps the celestial sky and can provide information from Wikipedia about celestial objects to the user. The stars, constellations, planets, sun, and moon are all rendered in real-time and the user can navigate the celestial map simply by pointing the device around the sky to find and identify the different celestial objects. However, if the user prefers, a manual touch-based map navigation feature is also available in StarMapper. While other Android applications currently exist for mapping the sky, such as Google's Sky Map, StarMapper aims to enhance the experience by also providing additional information about celestial objects to the user by means of a simple click on the screen. For obtaining more information about a particular constellation or other celestial object, the user only needs to click on the object's name in the map, and the device's web browser opens to the Wikipedia page of the clicked object. Through this simple mechanism, the user can learn much more about astronomy than just locations of celestial objects. / text

Given the popularity of Java, extending the standard Java virtual machine (JVM) to become cluster-aware effectively brings the vision of transparent horizontal scaling of applications to fruition. With a set of cluster-wide JVMs orchestrated as a virtually single system, thread-level parallelism in Java is no longer confined to one multiprocessor. An unmodified multithreaded Java application running on such a Distributed JVM (DJVM) can scale out transparently, tapping into the vast computing power of the cluster. While this notion creates an easy-to-use and powerful parallel programming paradigm, research on DJVMs has remained largely at the proof-of-concept stage where successes were proven using trivial scientific computing workloads only. Real-life Java applications with commercial server workloads have not been well-studied on DJVMs. Their natures including complex and sometimes huge object graphs, irregular access patterns and frequent synchronizations are key scalability hurdles. To design a scalable DJVM for real-life applications, we identify three major unsolved issues calling for a top-to-bottom overhaul of traditional systems. First, we need a more time- and space-efficient cache coherence protocol to support fine-grained object sharing over the distributed shared heap. The recent prevalence of concurrent data structures with heavy use of volatile fields has added complications to the matter. Second, previous generations of DJVMs lack true support for memory-intensive applications. While the network-wide aggregated physical memory can be huge, mutual sharing of huge object graphs like Java collections may cause nodes to eventually run out of local heap space because the cached copies of remote objects, linked by active references, can’t be arbitrarily discarded. Third, thread affinity, which determines the overall communication cost, is vital to the DJVM performance. Data access locality can be improved by collocating highly-correlated threads, via dynamic thread migration. Tracking inter-thread correlations trades profiling costs for reduced object misses. Unfortunately, profiling techniques like active correlation tracking used in page-based DSMs would entail prohibitively high overheads and low accuracy when ported to fine-grained object-based DJVMs. This dissertation presents technical contributions towards all these problems. We use a dual-protocol approach to address the first problem. Synchronized (lock-based) and volatile accesses are handled by a home-based lazy release consistency (HLRC) protocol and a sequential consistency (SC) protocol respectively. The two protocols’ metadata are maintained in a conflict-free, memory-efficient manner. With further techniques like hierarchical passing of lock ownerships, the overall communication overheads of fine-grained distributed object sharing are pruned to a minimal level. For the second problem, we develop a novel uncaching mechanism to safely break a huge active object graph. When a JVM instance runs low on free memory, it initiates an uncaching policy, which eagerly assigns nulls to selected reference fields, thus detaching some older or less useful cached objects from the root set for reclamation. Careful orchestration is made between uncaching, local garbage collection and the coherence protocol to avoid possible data races. Lastly, we devise lightweight sampling-based profiling methods to derive inter-thread correlations, and a profile-guided thread migration policy to boost the system performance. Extensive experiments have demonstrated the effectiveness of all our solutions. / published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy