We describe and evaluate a modified mark-and-sweep garbage collector for java Virtual Machines (JVMs) that allows applications to run using less memory. The modified algorithm not only removes from the heap objects th...
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ISBN:
(纸本)088986392X
We describe and evaluate a modified mark-and-sweep garbage collector for java Virtual Machines (JVMs) that allows applications to run using less memory. The modified algorithm not only removes from the heap objects that are no longer needed by a program (i.e., garbage), but also objects that have not been accessed for a sufficiently long time. The removal of such idling objects affects the reachability of other objects on the heap, and introduces overhead to both execution time and space requirements of the JVM. We describe how these issues are addressed, and evaluate the modified collector in the Sun Microsystems JDK 1.2.2 using applications from the SPECjvm98 benchmark suite. Our results indicate that it is possible to execute applications with up to 20% less memory, but at the expense of longer execution time. Our modified algorithm is useful when an application is to execute in a memory-constrained environment, where it normally runs out of memory.
A prototype Taskspaces framework for grid computing of scientific computing problems that require intertask communication is presented. The Taskspaces framework is characterized by three major design choices: decentra...
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ISBN:
(纸本)9781581136241
A prototype Taskspaces framework for grid computing of scientific computing problems that require intertask communication is presented. The Taskspaces framework is characterized by three major design choices: decentralization provided by an underlying tuple space concept, enhanced direct communication between tasks by means of a communication tuple space distributed over the worker hosts, and object orientation and platform independence realized by implementation in java. Grid administration tasks, for example resetting worker nodes, are performed by mobile agent objects. We report on large-scale grid computing experiments for iterative linear algebra applications showing that our prototype framework scales well for scientific computing problems that require neighbor-neighbor intertask communication. It is shown in a computational fluid dynamics simulation using a Lattice Boltzmann method that the Taskspaces framework can be used naturally in interactive collaboration mode. The scalable Taskspaces framework runs fully transparently on heterogeneous grids while maintaining a low complexity in terms of installation, maintenance, application programming and grid operation. It thus offers a promising roadway to push scientific grid computing with intertask communication beyond the experimental research setting.
Recent developments in service architectures suggest that run-time adaptations could be implemented with dynamic AOP. In this paper we discuss application requirements on run-time AOP support and present a system that...
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ISBN:
(纸本)1581136609
Recent developments in service architectures suggest that run-time adaptations could be implemented with dynamic AOP. In this paper we discuss application requirements on run-time AOP support and present a system that addresses these requirements. We provide basic support for weaving using the Just-In-Time compiler, while the AOP system is treated as an exchangeable module on top of the basic support. This approach allows us to provide low run-time over-head, AOP system flexibility, and secure weaving. We provide an extensive empirical evaluation and discuss the tradeoffs resulting from using the JIT compiler and a modularized architecture.
Foundational and scalable techniques for runtime safety analysis of multithreaded programs are explored in this paper. A technique based on vector clocks to extract the causal dependency order on state updates from a ...
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java is known to be a valuable technology for building platform independent applications, based on an independent execution environment provided by a virtual machine (JVM, java Virtual Machine) and an API formed by a ...
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java is known to be a valuable technology for building platform independent applications, based on an independent execution environment provided by a virtual machine (JVM, java Virtual Machine) and an API formed by a set of classes. The java platform was conceived as a solution for application transportation between heterogeneous platforms without the need of adapting and recompiling the source code. Some previous analyses of Sun JVM implementation (java 2 SDK 1.2.2-006) establish that the HPI (Host Porting Interface) layer does not abstract enough the concurrency offered by the underlying platform. Consequently, the execution of the same java application over distinct HPI platform implementations offers different behavior, being a possible cause of incorrect program execution. We consider that it's necessary a new HPI layer that can really abstract the concurrency supplied by the platform, giving a set of operations whose semantic does not vary between diverse platform implementations. With the new HPI, the JVM will be capable to perform a uniform behavior independently of the operating system. The new JVM with ULT offers an acceptable performance on multiprocessor architectures increasing the throughput and it implements a synchronization mechanism that achieves better results than the original JVM on SMP architectures.
We demonstrate QuickUML, a tool which supports iterative design and code development by providing facilities to draw UML class diagrams, to generate java code from such diagrams, and also to automatically generate a U...
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ISBN:
(纸本)1581137516
We demonstrate QuickUML, a tool which supports iterative design and code development by providing facilities to draw UML class diagrams, to generate java code from such diagrams, and also to automatically generate a UML class diagram from a collection of java source code files. We also discuss how use of the tool provides general support for teaching students the importance of design in software development.
A programming project which can be used in a course on object-orientation and graphical interface programming in java is discussed. The programming project is based on the board game known as wari. It is possible to s...
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ISBN:
(纸本)1581136722
A programming project which can be used in a course on object-orientation and graphical interface programming in java is discussed. The programming project is based on the board game known as wari. It is possible to step through a representative subset of the graphical element and progressing to a version of the code which is minimally graphical and progressing to a version with as many features as desired. The project would be adaptable to any book which covered the basic concepts of java, including object-orientation and the inclusion of graphical elements in programs.
The stability of the current Internet architecture depends mostly on end-to-end TCP congestion control mechanisms. The Network Congestion Analyzer and Controller (NCAC) is an effort to build a complete user interface ...
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A number of colleges and universities have recently added new degree programs in Information Technology (IT), or added IT components to existing Computer Science (CS) programs. javalanguage and technology are almost ...
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ISBN:
(纸本)1892512416
A number of colleges and universities have recently added new degree programs in Information Technology (IT), or added IT components to existing Computer Science (CS) programs. javalanguage and technology are almost inescapable elements of both CS and IT programs. One of java's more advanced features, language-level support for concurrency in the form of explicit multithreading, is important to both CS and IT students, but for different reasons. Teaching java concurrency to CS and IT students, therefore, presents different challenges and requires emphasizing the topic in different ways. We discuss these issues, and present our experiences from CS and IT classes taught recently, in which java concurrency was a topic.
The java Modeling language (JML) can be used to specify the detailed design of java classes and interfaces by adding annotations to java source files. The aim of JML is to provide a specification language that is easy...
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