MPJ Express is a thread-safe Java messaging library that provides a full implementation of the mpiJava 1.2 API specification. This specification defines a MPI-like bindings for the Java language. We have implemented two communication devices as part of our library, the first, called niodev is based on the Java New I/O package and the second, called mxdev is based on the Myrinet eXpress library. MPJ Express comes with an experimental runtime, which allows portable bootstrapping of Java Virtual Machines across a cluster or network of computers. In this paper we describe the implementation of MPJ Express. Also, we present a performance comparison against various other C and Java messaging systems. A beta version of MPJ Express was released in September 2005.

MPJ Express: Towards Thread Safe Java HPC

Concurrency: Practice and Experience

Computational grids have an enormous potential to provide compute power. However, this power remains largely unexploited today for most applications, except trivially parallel programs. Developing parallel grid applications simply is too difficult. Grids introduce several problems not encountered before, mainly due to the highly heterogeneous and dynamic computing and networking environment. Furthermore, failures occur frequently, and resources may be claimed by higher-priority jobs at any time.In this article, we solve these problems for an important class of applications: divide-and-conquer. We introduce a system called Satin that simplifies the development of parallel grid applications by providing a rich high-level programming model that completely hides communication. All grid issues are transparently handled in the runtime system, not by the programmer. Satin's programming model is based on Java, features spawn-sync primitives and shared objects, and uses asynchronous exceptions and an abort mechanism to support speculative parallelism.To allow an efficient implementation, Satin consistently exploits the idea that grids are hierarchically structured. Dynamic load-balancing is done with a novel cluster-aware scheduling algorithm that hides the long wide-area latencies by overlapping them with useful local work. Satin's shared object model lets the application define the consistency model it needs. If an application needs only loose consistency, it does not have to pay high performance penalties for wide-area communication and synchronization.We demonstrate how grid problems such as resource changes and failures can be handled transparently and efficiently. Finally, we show that adaptivity is important in grids. Satin can increase performance considerably by adding and removing compute resources automatically, based on the application's requirements and the utilization of the machines and networks in the grid.Using an extensive evaluation on real grids with up to 960 cores, we demonstrate that it is possible to provide a simple high-level programming model for divide-and-conquer applications, while achieving excellent performance on grids. At the same time, we show that the divide-and-conquer model scales better on large systems than the master-worker approach, since it has no single central bottleneck.

Satin: A high-level and efficient grid programming model

This paper proposes a fast and efficient concurrent technique for downloading large files from replicated FTP servers available over the Internet, Cloud and Grid environments. This technique utilizes the availability of replicated FTP servers to enhance file download times through concurrent downloads of file blocks. As this technique enhances the download time, it imposes no extra communication and processing overhead compared to other concurrent or parallel FTP techniques. The proposed technique requires no coordination between servers and relies on the features of TCP to provide an efficient load balancing mechanism among multiple heterogeneous replicated FTP servers. This mechanism also provides an efficient load balancing solution to efficiently utilize available network and server resources on dynamic environments with varying network and FTP servers' loads. The proposed technique has been implemented and evaluated and the results show considerable performance gains for file downloading compared to other approaches.

DDFTP: Dual-Direction FTP

A dual-direction technique for fast file downloads with dynamic load balancing in the Cloud

Many of the key features of file transfer mechanisms like reliable file transferring and parallel transferring are developed as part of the service. It makes very hard to re–use the same code for the different systems. We are trying to overcome this disadvantage by decoupling useful features of file transfer mechanisms from the implementation of the service and protocol, and instead placed into the messaging substrate. We may thus treat file transfer operations as a specific usage case for a more general messaging environment. This will allow us to provide file transfer quality of service to other file transfer tools that does not have same features.

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GridFTP and parallel TCP support in naradabrokering

The paper begins by considering what a grid computing environment might be, why it is demanded and how the authors' HP spmd programming fits into this picture. We then review our HP Java environment as a contribution towards programming support for high-performance grid-enabled environments. Future grid computing systems will need to provide programming models. In a proper programming model for grid-enabled environments and applications, high performance on multi-processor systems is a critical issue. We describe the features of HP Java, including run-time communication library, compilation strategies and optimization schemes. Through experiments, we compare HP Java programs against FORTRAN and ordinary Java programs. We aim to demonstrate that HP Java can be used “anywhere”—not only for high-performance parallel computing, but also for grid-enabled applications.

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HP Java: Programming Support for High-Performance Grid-Enabled Applications

Two characteristic run-time communication libraries of HPJava are developed as an application level library and device level library. A high-level communication API, Adlib, is developed as an application level communication library. This communication library supports collective operations on distributed arrays. The mpjdev API is a device level underlying communication library for HPJava. This library is developed to perform actual communication between processes. The paper describes the novel issues in the implementation of device level library on different platforms, and gives comprehensive benchmark results on a parallel platform. All software developed in this project is available for free download from www.hpjava.org. Procs2 p = new Procs2(P, P) ; on(p) { Range x = new BlockRange(M, p.dim(0)) ; Range y = new BlockRange(N, p.dim(1)) ; float [[-,-]] a = new float [[x, y]], b = new float [[x, y]], c = new float [[x, y]]; ... initialize values in `a', `b' overall(i = x for :) overall(j = y for :) c [i, j] = a [i, j] + b [i, j] ;

/pdf/a-device-level-communication-library-for-the-hpjava-3ykg1qfikx.pdf

A device level communication library for the hpjava programming language

We start seeing the authors’ HPspmd Programming Model 1 towards the programming support for HighPerformance Grid-Enabled Environments since the future grid computing systems will need to provide programming models. As a proper programming model for grid-enabled environments and applications, high performance on multi-processor systems is critical issue. We argue with simple experiments that we can in fact hope to achieve high performance in a similar ballpark to more traditional HPC languages.

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HPJava: Programming Support for High-Performance Grid-Enabled Applications.

Designing a simple but powerful low-level communication library for Java HPC environments is an important task. We introduce new low-level communication library for Java HPC, called mpjdev. The mpjdev API is designed with the goal that it can be implemented portably on network platforms and efficiently on parallel hardware. Unlike MPI which is intended for the application developer, mpjdev is meant for library developers. Application level communication may be implemented on top of mpjdev. The mpjdev API itself might be implemented on top of Java sockets in a portable network implementation, or-on HPC platforms-through a JNI (Java Native Interface) to a subset of MPI.

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Sang Boem Lim

Papers

GridFTP and parallel TCP support in naradabrokering

HP Java: Programming Support for High-Performance Grid-Enabled Applications

A device level communication library for the hpjava programming language

HPJava: Programming Support for High-Performance Grid-Enabled Applications.

A low–level communication library for java HPC