Real-Time MapReduce Scheduling

In this paper, we explore the feasibility of enabling the scheduling of mixed hard and soft real-time MapReduce applications. We first present an experimental evaluation of the popular Hadoop MapReduce middleware on the Amazon EC2 cloud. Our evaluation reveals tradeoffs between overall system throughput and execution time predictability, as well as highlights a number of factors affecting real-time scheduling, such as data placement, concurrent users, and master scheduling overhead. Based on our evaluation study, we present a formal model for capturing real-time MapReduce applications and the Hadoop platform. Using this model, we formulate the offline scheduling of real-time MapReduce jobs on a heterogeneous distributed Hadoop architecture as a constraint satisfaction problem (CSP) and introduce various search strategies for the formulation. We propose an enhancement of MapReduce’s execution model and a range of heuristic techniques for the online scheduling. We further outline some of our future directions that apply state-of-the-art techniques in the real-time scheduling literature

An Empirical Analysis of Scheduling Techniques for Real-Time Cloud-Based Data Processing

In this paper, we explore the challenges and needs of current cloud infrastructures, to better support cloud-based data-intensive applications that are not only latency-sensitive but also require strong timing guarantees. These applications have strict deadlines (e.g., to perform time-dependent mission critical tasks or to complete real-time control decisions using a human-in-the-loop), and deadline misses are undesirable. To highlight the challenges in this space, we provide a case study of the online scheduling of MapReduce jobs executed by Hadoop. Our evaluations on Amazon EC2 show that the existing Hadoop scheduler is ill-equipped to handle jobs with deadlines. However, by adapting existing multiprocessor scheduling techniques for the cloud environment, we observe significant performance improvements in minimizing missed deadlines and tardiness. Based on our case study, we discuss a range of challenges in this domain posed by virtualization and scale, and propose our research agenda centered around the application of advanced real-time scheduling techniques in the cloud environment

Phenolic Compound Profiles in Grape Skins of Cabernet Sauvignon, Merlot, Syrah and Marselan Cultivated in the Shacheng Area (China)

The phenolic compounds in the grape skins of Cabernet Sauvignon (CS), Merlot (ML), Syrah (SY) and Marselan (MS) from Shacheng, in China, were compared using HPLC-MS/MS. The results showed that the types and levels of phenolic compounds varied greatly with cultivars. Malvidin derivatives were the main anthocyanins. CS and ML showed a higher content of malvidin-3-O-(6-O-acetyl)-glucoside than malvidin-3-O-(trans-6-O- coumaryl)-glucoside, while SY and MS differed from CS and ML. ML had higher delphinidin and cyanidin derivatives, SY had higher peonidin derivatives, while malvidin and petunidin were higher in MS. The total content of flavonols, flavan-3-ols, phenolic acids and stilbenes in grape skins showed no difference among CS, ML and MS. Isorhamnetin-3-O-glucoside (CS, ML, MY), quercetin-3O-glucoside (SY), procyanidin trimer (SY, MS), procyanidin dimer (CS, ML), syringetin-3-O-glucoside, trans-cinnamic acid and resveratrol were the most abundant non-anthocyanin phenolic compounds. Cluster analysis showed that CS and ML, and SY and MS had similar phenolic profiles

Cost-Based Dynamic Job Rescheduling: A Case Study of the Intel Distributed Computing Platform

We perform a trace-driven analysis of the Intel Distributed Computing Platform (IDCP), an Internet-scale data center based distributed computing platform developed by Intel Corporation for massively parallel chip simulations within the company. IDCP has been operational for many years, and currently is deployed “live” on tens of thousands of machines that are globally distributed at various data centers. Our analysis is performed on job execution traces obtained over a one year period collected from tens of thousands of IDCP machines from 20 different pools. Our analysis demonstrates that job completion time can be severely impacted due to job suspension when higher priority jobs preempt lower priority jobs. We then develop cost-based dynamic job rescheduling strategies that adaptively restart suspended jobs, which better utilize system resources and improve completion times. Our trace-driven evaluation results show that dynamic rescheduling enables IDCP to significantly reduce job completion times

On the Feasibility of Dynamic Rescheduling on the Intel Distributed Computing Platform

This paper examines the feasibility of dynamic rescheduling techniques for effectively utilizing compute resources within a data center. Our work is motivated by practical concerns of Intel’s NetBatch system, an Internet-scale data center based distributed computing platform developed by Intel Corporation for massively parallel chip simulations within the company. NetBatch has been operational for many years, and currently is deployed live on tens of thousands of machines that are globally distributed at various data centers. We perform an analysis of job execution traces obtained over a one year period collected from tens of thousands of NetBatch machines from 20 different pools. Our analysis show that we observe that the NetBatch currently does not make full use of all the resources. Specifically, the job completion time can be severely impacted due to job suspension when higher priority jobs preempt lower priority jobs. We then develop dynamic job rescheduling strategies that adaptively restart jobs to available resources elsewhere, which better utilize system resources and improve completion times. Our trace-driven evaluation results show that dynamic rescheduling enables NetBatch to significantly reduce system waste and completion time of suspended jobs

Strength enhancement of aluminium honeycombs caused by entrapped air underdynamic out-of-plane compression

The out-of-plane crushing behaviour of aluminium hexagonal honeycombs containing different percentages of holes (i.e., the fraction of penetrated cells to the total) was extensively investigated over a wide range of strain rates where each test was conducted at constant compression velocity. Strength enhancement due to the increase of the strain rate and the entrapped air was studied. It is found that the strain hardening of honeycomb structures during the dynamic crush is mostly attributed to the pressure change caused by the entrapped air. The leaking rate, δ̇, was then studied and found to be dependent on the strain and strain rate, and independent of the wall thickness to edge length ratio, t/l. An empirical constitutive relation describing the plastic collapse stress in relation to the t/l ratio, the strain and strain rate is proposed, which agrees well with the experimental results. © 2012 Elsevier Ltd. All rights reserved.S. Xu, J.H. Beynon, D. Ruan, T.X. Y

The effect of size and composition on structural transitions in monometallic nanoparticles

Predicting the morphological stability of nanoparticles is an essential step towards the accurate modelling of their chemophysical properties. Here we investigate solid–solid transitions in monometallic clusters of 0.5–2.0 nm diameter at finite temperatures and we report the complex dependence of the rearrangement mechanism on the nanoparticle’s composition and size. The concerted Lipscomb’s Diamond-Square-Diamond mechanisms which connects the decahedral or the cuboctahedral to the icosahedral basins, take place only below a material dependent critical size above which surface diffusion prevails and leads to low-symmetry and defected shapes still belonging to the initial basin

Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station

A precise measurement of the proton flux in primary cosmic rays with rigidity (momentum/charge) from 1 GV to 1.8 TV is presented based on 300 million events. Knowledge of the rigidity dependence of the proton flux is important in understanding the origin, acceleration, and propagation of cosmic rays. We present the detailed variation with rigidity of the flux spectral index for the first time. The spectral index progressively hardens at high rigidities.</p

Axially loaded pressurized thin-walled circular tubes used as adaptive energy absorbers

By filling compressed air into cellular materials, honeycombs or thin-walled structures, their energy absorption can be greatly enhanced, while this enhancement can be controlled by the applied pressure. This concept shines a light on the possibility of achieving adaptive energy absorption. To investigate the effect of the internal pressure on the response of the structures under impact loadings, the present paper reports our study on the axial crushing behavior of pressurized thin-walled circular tubes. Three groups of thin-walled circular tubes with the radius/thickness ratio between 120 and 200 were employed in the experiments and two working modes were studied: mode-I (with constant internal pressure) and mode-II (closed tubes with finite leakage). In the tests of mode-I, the influences of internal pressure on the deformation mode and energy absorption of the tubes were investigated. The results show that with the increase of internal pressure, the deformation mode switches from diamond mode with sharp corners to that with round corners, and eventually to ring mode. In diamond mode, the mean force of the tubes increases linearly with the internal pressure. The enhancement comes from two mechanisms: direct effect of the pressure and indirect effect due to the interaction between the pressure and the tube wall. After the deformation switches to ring mode, the enhancement resulted from the second mechanism becomes weaker. Based on the results of mode-I, the mode-II was experimentally investigated both quasi-statically and dynamically. The results are compared with the predictions obtained from a semi-empirical formula, showing good agreements. Copyright © 2008 by ASME