Konrad Zuse's Z3, built in Berlin from 1938 to 1941, was destroyed during World War II. The reconstruction project started in 1994. A functional replica was built and unveiled at a conference commemorating the 60t...
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Konrad Zuse's Z3, built in Berlin from 1938 to 1941, was destroyed during World War II. The reconstruction project started in 1994. A functional replica was built and unveiled at a conference commemorating the 60th anniversary of the public presentation of the original machine in 2001. The reconstruction project includes several java simulations of components of the whole machine and a 3D functional simulation of the Z3 and its user console.
The paper describes a distributed brute-force attack on RC5 cipher using java applets. It introduces a novel model for long-term parallel computing based on the abstraction of solvers with limited lifetime, The associ...
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The paper describes a distributed brute-force attack on RC5 cipher using java applets. It introduces a novel model for long-term parallel computing based on the abstraction of solvers with limited lifetime, The associated problems and scheduling policy are discussed. The paper comments on the inherent performance problems of the java Virtual Machine and presents performance measurements of the cipher breaking applet for several computing platforms. (C) 1998 John Whey & Sons, Ltd.
The trend towards processors with more and more parallel cores is increasing the need for software that can take advantage of parallelism. The most widespread method for writing parallel software is to use explicit th...
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The trend towards processors with more and more parallel cores is increasing the need for software that can take advantage of parallelism. The most widespread method for writing parallel software is to use explicit threads. Writing correct multithreaded programs, however, has proven to be quite challenging in practice. The key difficulty is non-determinism. The threads of a parallel application may be interleaved non-deterministically during execution. In a buggy program, nondeterministic scheduling can lead to nondeterministic results—where some interleavings produce the correct result while others do not. We propose an assertion framework for specifying that regions of a parallel program behave deterministically despite nondeterministic thread interleaving. Our framework allows programmers to write assertions involving pairs of program states arising from different parallel schedules. We describe an implementation of our deterministic assertions as a library for java, and evaluate the utility of our specifications on a number of parallel java benchmarks. We found specifying deterministic behavior to be quite simple using our assertions. Further, in experiments with our assertions, we were able to identify two races as true parallelism errors that lead to incorrect nondeterministic behavior. These races were distinguished from a number of benign races in the benchmarks. [ABSTRACT FROM AUTHOR]
The growing scale of available commercial multicore systems has increased the need for concurrent programming, because these systems expose hardware parallelism to the programmer that must be explicitly managed in sof...
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The growing scale of available commercial multicore systems has increased the need for concurrent programming, because these systems expose hardware parallelism to the programmer that must be explicitly managed in software. Commercial software developers that are traditionally skilled in sequential programming are now forced to reason about concurrency to exploit multicore parallelism. More than ever, this new group of concurrent programmers has to rely on performance tools for help. This paper introduces a new tool called THOR, which addresses the complexities introduced by multicore parallelism by organizing views in terms of java (R) threads and using vertical profiling techniques to understand the state of a java thread at all layers of the execution stack. Data collection supports visualization by tagging each trace event with a corresponding thread identifier and with a time-stamp from the machine's high-resolution timer. By exhaustively tracing fine-grain events, such as operating system context switches and java lock contention, data collection allows a user to utilize visualization to reconstruct the precise behavior of his application. In this paper, we present the details of the THOR architecture and design. THOR is currently available from IBM alphaWorks (R) as part of the multicore software development kit.
Developing parallel applications is notoriously difficult, but it\'s even more complex for desktop applications. The added difficulties primarily come from their interactive nature, where users largely perceive th...
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Developing parallel applications is notoriously difficult, but it\'s even more complex for desktop applications. The added difficulties primarily come from their interactive nature, where users largely perceive their performance. Desktop applications are typically developed with graphical toolkits that in turn have limitations in regards to multithreading. This article explores desktop applications\' structure, the threading model\'s limitations, and the parallelization of a desktop application using object-oriented and GUI-aware concepts.
With an interactive simulation of the ENIAC, users can wire complex configurations of the machine's modules. The simulation, written in java, can be started from an Internet site. The simulation has been tested wi...
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With an interactive simulation of the ENIAC, users can wire complex configurations of the machine's modules. The simulation, written in java, can be started from an Internet site. The simulation has been tested with a 6-meter-long data wall, which provides the closest available approximation to the look and feel of programming this historical computer.
Three placement algorithms are presented that may be employed for the automatic generation of one-line diagrams of power systems. To demonstrate the ability of these algorithms, a one-line diagram auto generation soft...
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Three placement algorithms are presented that may be employed for the automatic generation of one-line diagrams of power systems. To demonstrate the ability of these algorithms, a one-line diagram auto generation software program (ODAG) has been developed. ODAG has been implemented using the java programming language so that it is network accessible over the Internet as a one-line diagram design tool. Algorithms implemented in ODAG include Spring Embedder, Rooted Tree and Controlled Spring Embedder with Grid Aligning. They autogenerate one-line diagram layouts that are aesthetically pleasing with acceptable readability and user friendliness. Two networks have been used as examples in the paper to illustrate the one-line diagrams autogenerated by these algorithms.
The JPVM library is a software system for explicit message-passing-based parallel programming in java. The library supports an interface similar to the C and Fortran interface of the parallel virtual machine (PVM) sys...
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The JPVM library is a software system for explicit message-passing-based parallel programming in java. The library supports an interface similar to the C and Fortran interface of the parallel virtual machine (PVM) system, with modifications to better suit javaprogramming styles, The similarity between JPVM and the widely used PVM system supports a quick learning curve for experienced PVM programmers, At the same time, JPVM offers novel features not found in standard PVM such as thread safety, multiple communication end-points per task, and default-case direct message routing. JPVM is implemented entirely in java, and is thus highly portable among platforms supporting a version of the java Virtual Machine. This feature opens up the possibility of utilizing resources such as Macintosh and Windows based workstations, which are commonly excluded from network parallel computing systems. Initial applications performance results achieved with a prototype JPVM system indicate that the java-implemented approach can offer good performance at appropriately coarse granularities. (C) 1998 John Whey & Sons, Ltd.
Due to its platform-independent execution model, its support for networking, multithreading and mobile code, java has given hope that easy Internet-wide high-performance network computing was at hand. Numerous attempt...
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Due to its platform-independent execution model, its support for networking, multithreading and mobile code, java has given hope that easy Internet-wide high-performance network computing was at hand. Numerous attempts have then been made at providing a framework for the development of such metacomputing applications. Unfortunately, none of them addresses seamless sequential, multithreaded and distributed computing, i.e. the execution of the same application on a multiprocessor shared-memory machine as well as on a network of workstations, or on any hierarchical combination of both. In this paper we first identify four requirements for the development of such metacomputing frameworks. We then introduce java// (pronounced java Parallel), a 100% java library that provides transparent remote objects as well as asynchronous two-way cabs, high reuse potential and high-level synchronization mechanisms. We also present the metaobject protocol (MOP) java// is built on and describe a distributed collaborative raytracing test application built using java//, (C) 1998 John Whey & Sons, Ltd.
When the java programming language was introduced by Sun Microsystems in 1995, there was a perception (properly founded at the time) that its many benefits came at a significant performance cost. The related deficienc...
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When the java programming language was introduced by Sun Microsystems in 1995, there was a perception (properly founded at the time) that its many benefits came at a significant performance cost. The related deficiencies were especially apparent in numerical computing. Our own measurements in 1997 with second-generation java Virtual Machines (JVMs) found differences in performance of up to one hundredfold relative to C and Fortran. Initial experience with poor performance caused many developers of high-performance numerical applications to reject java out-of-hand as a platform for their applications.
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