1,144 research outputs found
A Cyclic Distributed Garbage Collector for Network Objects
This paper presents an algorithm for distributed garbage collection and outlines its implementation within the Network Objects system. The algorithm is based on a reference listing scheme, which is augmented by partial tracing in order to collect distributed garbage cycles. Processes may be dynamically organised into groups, according to appropriate heuristics, to reclaim distributed garbage cycles. The algorithm places no overhead on local collectors and suspends local mutators only briefly. Partial tracing of the distributed graph involves only objects thought to be part of a garbage cycle: no collaboration with other processes is required. The algorithm offers considerable flexibility, allowing expediency and fault-tolerance to be traded against completeness
A model-based approach for automatic recovery from memory leaks in enterprise applications
Large-scale distributed computing systems such as data centers are hosted on heterogeneous and networked servers that execute in a dynamic and uncertain operating environment, caused by factors such as time-varying user workload and various failures. Therefore, achieving stringent quality-of-service goals is a challenging task, requiring a comprehensive approach to performance control, fault diagnosis, and failure recovery. This work presents a model-based approach for fault management, which integrates limited lookahead control (LLC), diagnosis, and fault-tolerance concepts that: (1) enables systems to adapt to environment variations, (2) maintains the availability and reliability of the system, (3) facilitates system recovery from failures. We focused on memory leak errors in this thesis. A characterization function is designed to detect memory leaks. Then, a LLC is applied to enable the computing system to adapt efficiently to variations in the workload, and to enable the system recover from memory leaks and maintain functionality
Programming with process groups: Group and multicast semantics
Process groups are a natural tool for distributed programming and are increasingly important in distributed computing environments. Discussed here is a new architecture that arose from an effort to simplify Isis process group semantics. The findings include a refined notion of how the clients of a group should be treated, what the properties of a multicast primitive should be when systems contain large numbers of overlapping groups, and a new construct called the causality domain. A system based on this architecture is now being implemented in collaboration with the Chorus and Mach projects
Reliability issues in the design of distributed object-based architectures
PhD ThesisThis thesis is aimed at enhancing the existing set of techniques for building
distributed systems, specifically from the point of view of fault-tolerant com-
puting.
Reliability is of fundamental importance in the design and operation of dis-
tributed systems, as an increasing number of computers are employed in the
automation of various essential services. In the past decade, much research
effort has been concerned with the object-based methodology for the design
and implementation of reliable distributed systems.
This thesis describes three contributions to this effort. First, it is shown
that object-based programming features can in fact be introduced into pro-
cedural languages provided that these languages are endowed with certain
facilities. Then, work is discussed which illustrates the relationship
between distributed object-based architectures and an apparently different
form of distributed architectures based on processes. This work puts the
notion of object-based architectures into a new perspective, which shows
that the object-based philosophy and the process-based philosophy are the
dual of each other.
Finally, an important aspect of the design of an object-based distributed
architecture is investigated, that of automatic garbage collection. A distri-
buted garbage collection scheme is described that handles fault tolerance by
an extension of the technique commonly employed to detect unwanted com-
putations in distributed architectures. The scheme proposed can also be
seen as yet a further illustration of the link between object-based and
process-based architectures.Royal Signals and Radar Establishment of the U.K.
Ministry of Defence.
Italian Consiglio Nazionale delle Ricerch
Designing application software in wide area network settings
Progress in methodologies for developing robust local area network software has not been matched by similar results for wide area settings. The design of application software spanning multiple local area environments is examined. For important classes of applications, simple design techniques are presented that yield fault tolerant wide area programs. An implementation of these techniques as a set of tools for use within the ISIS system is described
- …