6558101
The design and implementation of a fault-tolerant RPC system: Ninf-C
We describe the design and implementation of a fault tolerant GridRPC system, Ninf-C, designed for easy programming of large-scale master-worker programs that take from few days to few months for its execution in a grid environment. Ninf-C employs Condor, developed at University of Wisconsin, as the underlying middleware supporting remote file transmission and checkpointing for system-wide robustness for application users on the grid. Ninf-C layers all the GridRPC communication and task parallel programming features on top of Condor in a non-trivial fashion, assuming that the entire program is structured in a master-worker style-in fact, older Ninf master-worker programs can be run directly or trivially ported to Ninf-C. In contrast to the original Ninf, Ninf-C exploits and extends Condor features extensively for robustness and transparency, such as 1) checkpointing and stateful recovery of the master process, 2) the master and workers mutually communicating using (remote) files, not IP sockets, and 3) automated throttling of parallel GridRPC calls; and in contrast to using Condor directly, programmers can set up complex dynamic workflow as well as master-worker parallel structure with almost no learning curve involved. To prove the robustness of the system, we performed an experiment on a heterogeneous cluster that consists of x86 and SPARC CPUs, and ran a simple but long-running master-worker program with staged rebooting of multiple nodes to simulate some serious fault situations. The program execution finished normally avoiding all the fault scenarios, demonstrating the robustness of Ninf-C.
14481721
Dynamic Resource Allocation Based on On-the-Fly Reservation
Resource reservation is a vital issue for grid-enabled programs to execute smoothly. Instead of using metascheduling solutions to request grid resources statically, we are developing a tiny C++ library to reserve on-demand computing resources based on Globus Toolkit, local schedulers such as Maui, and SQLite database. The interface class is named CReservation in the library. At the time of preparing this paper, the only implementation available is for Maui scheduler. With such implementation classes, one can request, release, and monitor reservations of computing resources dynamically. To verify the simplicity, usability, and stability of current library, we have performed an in-depth case study with a grid enabled hybrid MD/QM (Molecular Dynamics/Quantum Mechanical) multi-scale simulation program. Our test shows that this library provides an easy and effective approach to manage resource reservations from within grid-enabled applications.
13964619
Parallelization of Saprse Cholesky Factorization on an SMP Cluster
In this paper, we present parallel implementations of the sparse Cholesky factorization kernel in the SPLASH-2 programs to evaluate performance of a Pentium Pro based SMP cluster. Solaris threads and remote memory operations are utilized for intranode parallelism and internode communications, respectively. Sparse Cholesky factorization is a typical irregular application with a high communication to computation ratio and no global synchronization between steps. We efficiently parallelized using asynchronous message handling instead of lock-based mutual exclusion between nodes, because synchronization between nodes reduces the performance significantly. We also found that the mapping of processes to processors on an SMP cluster affects the performance especially when the communication latency can not be hidden.
15968684
GEO Grid: Grid Infrastructure for Integration of Huge Satellite Imagery and Geoscience Data Setsets
We have designed Global Earth Observation(GEO) Grid, which is an infrastructure for archiving and processing huge satellite imagery and GIS geographical data sets. Users can immediately access the full archive and process the desired data areas on demand using the latest calibration and analysis algorithms through standardized web services interfaces on basic OGSA services. GEO Grid is based on four layers, hardware, virtual storage, application and data services, and user interface. Each layer has the potential for extendability. We constructed GEO Grid to process satellite data taken by ASTER launched at the end of 1999 as an EOS project.
2787964
Implementation of Fault-Tolerant GridRPC Applications
A task parallel application is implemented with Ninf-G, a GridRPC system. A series of experiments are conducted on the Grid testbed in Asia Pacific for three months. Through tens of long executions, typical fault patterns were collected, and instability of the network throughput was determined to be a major reason of the faults. Several important points are stressed to avoid task throughput decline due to the fault-recovery operations: Timeout minimization for fault detection, background recovery, redundant task assignments, and so on. This study also issues a steer for design of the automated fault-tolerant mechanism in an upper layer of the GridRPC framework.
11192988
Design and Implementation of Distributed Task Sequencing on GridRPC
In the framework of GridRPC, a new function that allows direct data transfer between RPC servers is implemented for efficient execution of a Task Sequencing job in a grid environment. In Task Sequencing, RPC requires dependency between input and output parameters, which means output of a previous RPC becomes the input of the next RPC. In this study, the direct transfer of data is implemented using the grid filesystem without destroying the GridRPC programming model and without changing very many parts of the existing Ninf-G implementation. Our Task Sequencing API library analyzes RPC arguments to detect intermediate data after task submissions, and reports the information to GridRPC servers so that the intermediate data is created on the grid filesystem. Through our performance evaluation on LAN and on the Japan-US grid environment, it was verified that the function achieved performance improvement in distributed Task Sequencing.
27048178
Mechanism and control of mobile pipeline maintenance robot with lazy tongs mechanism
A new type of mobile pipeline maintenance robot has been designed to clarify the feasibility of lazy tongs mechanism for adaptation to various size pipelines. The robot basically consists of three modules with two joints between modules and can move straight and spirally along the surface of pipeline. The robot can change its arm length in order to move on the pipeline of various size from 25 A to 100 A, and pass over obstacles such as reducer, diffuser, flange and other plant equipment. The control of the robot is so complicated that the modified dual control mode is introduced using the coordinate transformation matrix. By calculating the position and attitude of the robot under the control mode, the manoeuvrability of passing over a reducer is shown with experimental results.
42879781
Vision based navigation system by variable template matching for autonomous mobile robot
We have previously developed a navigation system for autonomous mobile robots. It can find landmarks on the ceiling to move and work. However, it is impossible to recognize landmarks when the size of landmark is different from the size of template. In such cases, the robot cannot continue to work. Therefore we proposed variable template matching (VTM) that makes it possible to recognize landmarks of different sizes. We realize VTM by using the optimization method called the evolution strategy (ES). The robot can recognize the landmark faster, inferring landmark parameters by binary density projection.