著者

Iwata Satoshi Kono Kenji

出版者

Information Processing Society of Japan

雑誌

IPSJ Online Transactions (ISSN:18826660)

巻号頁・発行日

vol.5, pp.1-12, 2012

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Performance anomalies in web applications are becoming a huge problem and the increasing complexity of modern web applications has made it much more difficult to identify their root causes. The first step toward hunting for root causes is to narrow down suspicious components that cause performance anomalies. However, even this is difficult when several performance anomalies simultaneously occur in a web application; we have to determine if their root causes are the same or not. We propose a novel method that helps us narrow down suspicious components called <i>performance anomaly clustering</i>, which clusters anomalies based on their root causes. If two anomalies are clustered together, they are affected by the same root cause. Otherwise, they are affected by different root causes. The key insight behind our method is that anomaly measurements that are negatively affected by the same root cause deviate similarly from standard measurements. We compute the similarity in deviations from the non-anomalous distribution of measurements, and cluster anomalies based on this similarity. The results from case studies, which were conducted using RUBiS, which is an auction prototype modeled after eBay.com, are encouraging. Our clustering method output clusters crucial in the search for root causes. Guided by the clustering results, we searched for components exclusively used by each cluster and successfully determined suspicious components, such as the Apache web server, Enterprise Beans, and methods in Enterprise Beans. The root causes we found were shortages in network connections, inadequate indices in the database, and incorrect issues with SQLs, and so on.

著者

Masahiro Ide Kimio Kuramitsu

出版者

一般社団法人 情報処理学会

雑誌

IPSJ Online Transactions (ISSN:18826660)

巻号頁・発行日

vol.6, pp.9-16, 2013 (Released:2013-01-29)

参考文献数

11

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In recent years, as a method to improve the language performance of scripting languages has attracted the attention of the Just-In-Time (JIT) compilation techniques for scripting language. The difficulty of JIT compilation for scripting language is its dynamically typed code and in its own language runtime. The purpose of this paper is to evaluate the performance overhead of JIT compilation of runtime library's overhead by using a statically typed scripting language. In this study, we use a statically typed scripting language KonohaScript to analyze language runtime performance impact of the code generated by the JIT compiler.

著者

Eiko Takaoka Takayuki Yonezu Takafumi Namekawa

出版者

Information Processing Society of Japan

雑誌

IPSJ Online Transactions (ISSN:18826660)

巻号頁・発行日

vol.8, pp.1-8, 2015 (Released:2015-01-27)

参考文献数

25

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We designed, developed, and evaluated computer programming education at high schools and universities in 2012 and 2013 to offer students an opportunity to experience practical programming. We provided a programming course to a high school, preparing content-rich materials. In order to generate motivation for learning in students, we set “to create practical applications” as a goal of the course. In 2012, only a few students could create practical applications; however, in 2013, we improved the teaching methods and by the end of the course, almost half of the participants were able to produce practical applications. In addition, some students applied their programs for the Live E! science contest and they received prizes in 2012 and two students applied and one of them received a prize in 2013. An additional notable outcome of the course that we provided was the extent to which first-year students became interested in programming.

著者

Jun Kitazono Toshiaki Omori Toru Aonishi Masato Okada

出版者

一般社団法人 情報処理学会

雑誌

IPSJ Online Transactions (ISSN:18826660)

巻号頁・発行日

vol.5, pp.186-191, 2012 (Released:2012-10-03)

参考文献数

22

被引用文献数

1 3

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With developments in optical imaging over the past decade, statistical methods for estimating dendritic membrane resistance from observed noisy signals have been proposed. In most of previous studies, membrane resistance over a dendritic tree was assumed to be constant, or membrane resistance at a point rather than that over a dendrite was investigated. Membrane resistance, however, is actually not constant over a dendrite. In a previous study, a method was proposed in which membrane resistance value is expressed as a non-constant function of position on dendrite, and parameters of the function are estimated. Although this method is effective, it is applicable only when the appropriate function is known. We propose a statistical method, which does not express membrane resistance as a function of position on dendrite, for estimating membrane resistance over a dendrite from observed membrane potentials. We use the Markov random field (MRF) as a prior distribution of the membrane resistance. In the MRF, membrane resistance is not expressed as a function of position on dendrite, but is assumed to be smoothly varying along a dendrite. We apply our method to synthetic data to evaluate its efficacy, and show that even when we do not know the appropriate function, our method can accurately estimate the membrane resistance.

著者

Hajime Fujita Yutaka Ishikawa

出版者

Information Processing Society of Japan

雑誌

IPSJ Online Transactions (ISSN:18826660)

巻号頁・発行日

vol.4, pp.73-83, 2011 (Released:2011-03-18)

参考文献数

22

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In this paper we propose DTS (Distributed TCP Splicing), a new mechanism for performing content-aware TCP connection switching in a broadcast-based single IP address cluster. Broadcast-based design enables each cluster node to continue to provide services to clients even when other nodes in the cluster fail. Each connection request from a client is first distributed among the cluster using the consistent hashing method, in order to share the request inspection workload. Then the connection is transferred to an appropriate node according to the content of the request. DTS is implemented on the Linux kernel module and does not require any modification to the main kernel code, server applications, or client applications. With an 8-node server configuration, a DTS cluster with multiple request inspectors achieves about 3.4 times higher connection throughput compared to the single inspector configuration. A SPECweb 2005 Support benchmark is also conducted with a four node cluster, where DTS reduces the total amount of disk accesses with a locality-aware request distribution and almost halves the number of file downloads that fail to meet the speed requirement.