Towards a green ranking for programming languages

While in the past the primary goal to optimize software was the run time optimization, nowadays there is a growing awareness of the need to reduce energy consumption. Additionally, a growing number of developers wish to become more energy-aware when programming and feel a lack of tools and the knowledge to do so.In this paper we define a ranking of energy efficiency in programming languages. We consider a set of computing problems implemented in ten well-known programming languages, and monitored the energy consumed when executing each language. Our preliminary results show that although the fastest languages tend to be the lowest consuming ones, there are other interesting cases where slower languages are more energy efficient than faster ones.This work is financed by the ERDF - European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT - Fundacao para a Ciencia e a Tecnologia within project POCI-01-0145-FEDER-016718. The second author is also sponsored by FCT grant SFRH/BD/112733/2015

PERFORMANCE ANALYSIS BETWEEN INTERPRETED LANGUAGE-BASED (LARAVEL) AND COMPILED LANGUAGE-BASED (GIN) WEB FRAMEWORKS

Web frameworks are essential for web developers, allowing them to build web applications more efficiently and effectively. This research paper compared two web frameworks with different programming language implementations: interpreted programming language and compiled programming language. PHP/Laravel was chosen as the representative interpreted programming language, and Go/Gin was chosen as the representative compiled programming language, because they were the most popular based on their star counts on GitHub. Based on a research paper by the University of Minho, Go was nearly 10 times faster than PHP in terms of execution time. Despite this, PHP is still the most commonly used web technology among the top 1 million websites. The results of a series of tests comparing the two showed that Gin was over 86 times faster than Laravel in terms of requests per second and time per request. The choice of which web framework to use will depend on the specific needs and goals of the project. However, if performance is the only criterion, then Gin is a better choice than Laravel.Web frameworks are essential for web developers, allowing them to build web applications more efficiently and effectively. This research paper compared two web frameworks with different programming language implementations: interpreted programming language and compiled programming language. PHP/Laravel was chosen as the representative interpreted programming language, and Go/Gin was chosen as the representative compiled programming language, because they were the most popular based on their star counts on GitHub. Based on a research paper by the University of Minho, Go was nearly 10 times faster than PHP in terms of execution time. Despite this, PHP is still the most commonly used web technology among the top 1 million websites. The results of a series of tests comparing the two showed that Gin was over 86 times faster than Laravel in terms of requests per second and time per request. The choice of which web framework to use will depend on the specific needs and goals of the project. However, if performance is the only criterion, then Gin is a better choice than Laravel

E-Debitum: managing software energy debt

35th IEEE/ACM International Conference on Automated Software Engineering Workshops (ASEW ’20) - International Workshop on Sustainable Software Engineering (SUSTAIN-SE)This paper extends previous work on the concept of a new software energy metric: Energy Debt. This metric is a reflection on the implied cost, in terms of energy consumption over time, of choosing an energy flawed software implementation over a more robust and efficient, yet time consuming, approach. This paper presents the implementation a SonarQube tool called E-Debitum which calculates the energy debt of Android applications throughout their versions. This plugin uses a robust, well defined, and extendable smell catalogue based on current green software literature, with each smell defining the potential energy savings. To conclude, an experimental validation of E-Debitum was executed on 3 popular Android applications with various releases, showing how their energy debt fluctuated throughout releases.This work is financed by National Funds through the Portuguese funding agency, FCT -Fundação para a Ciência e a Tecnologia within project UIDB/50014/2020

Energy efficiency across programming languages: how do energy, time, and memory relate?

This paper presents a study of the runtime, memory usage and energy consumption of twenty seven well-known software languages. We monitor the performance of such languages using ten different programming problems, expressed in each of the languages. Our results show interesting findings, such as, slower/faster languages consuming less/more energy, and how memory usage influences energy consumption. We show how to use our results to provide software engineers support to decide which language to use when energy efficiency is a concern.We would like to thank Luis Cruz (University of Porto) for the help that he provided. This work is financed by the ERDF - European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 Programme within project POCI-01-0145-FEDER-006961, and by National Funds through the Portuguese funding agency, FCT - Fundacao para a Ciencia e a Tecnologia within project POCI-01-0145-FEDER-016718 and UID/EEA/50014/2013. The first author is also sponsored by FCT grant SFRH/BD/112733/2015

Comparing the performance of string operations across programming languages

Abstract. In this thesis, the performance of string operations are compared across programming languages. Handling strings effectively is important especially when performance is a crucial factor and large string sizes may emerge. Common examples where large string sizes emerge are during digitalization of a product, reading string data from a database, reading and handling large CSV-files and Excel-files, converting file format to another file format (e.g. CSV to Excel and vice versa), and reading and handling a DOM-tree of a website. There has been a lot of corresponding research where programming languages are benchmarked, but none of them focus directly on string operations. The main goal of this thesis is to fill this gap in literature and try to find out which programming languages have the best results on string operations in terms of execution time and memory (maximum RSS) usage. The test environment was formed by creating randomly generated string files with sizes varying from ten thousand characters to 100 million characters. The generated characters were ‘a’, ‘b’, and ‘ ‘ (whitespace character). The programming languages selected for this thesis were Python, C, C++, Java, Perl, Ruby, Go, and Swift. Go seemed to be the most effective language in execution times, although it was not the fastest in many operations. C used very little memory, but only five operations were implemented in it. Every operation was implemented in Python, and it used additional memory to loading the string file in only one operation, which was sorting a string. Swift had quite bad results, and this could be caused by the Linux version of Swift that was used. In regular expressions, Perl and C++ were overwhelmingly effective. Java used the most memory in every operation

Energyware engineering: techniques and tools for green software development

Tese de Doutoramento em Informática (MAP-i)Energy consumption is nowadays one of the most important concerns worldwide. While hardware is generally seen as the main culprit for a computer’s energy usage, software too has a tremendous impact on the energy spent, as it can cancel the efficiency introduced by the hardware. Green Computing is not a newfield of study, but the focus has been, until recently, on hardware. While there has been advancements in Green Software techniques, there is still not enough support for software developers so they can make their code more energy-aware, with various studies arguing there is both a lack of knowledge and lack of tools for energy-aware development. This thesis intends to tackle these two problems and aims at further pushing forward research on Green Software. This software energy consumption issue is faced as a software engineering question. By using systematic, disciplined, and quantifiable approaches to the development, operation, and maintenance of software we defined several techniques, methodologies, and tools within this document. These focus on providing software developers more knowledge and tools to help with energy-aware software development, or Energyware Engineering. Insights are provided on the energy influence of several stages performed during a software’s development process. We look at the energy efficiency of various popular programming languages, understanding which are the most appropriate if a developer’s concern is energy consumption. A detailed study on the energy profiles of different Java data structures is also presented, alongwith a technique and tool, further providing more knowledge on what energy efficient alternatives a developer has to choose from. To help developers with the lack of tools, we defined and implemented a technique to detect energy inefficient fragments within the source code of a software system. This technique and tool has been shown to help developers improve the energy efficiency of their programs, and even outperforming a runtime profiler. Finally, answers are provided to common questions and misconceptions within this field of research, such as the relationship between time and energy, and howone can improve their software’s energy consumption. This thesis provides a great effort to help support both research and education on this topic, helps continue to grow green software out of its infancy, and contributes to solving the lack of knowledge and tools which exist for Energyware Engineering.Hoje em dia o consumo energético é uma das maiores preocupações a nível global. Apesar do hardware ser, de umaforma geral, o principal culpado para o consumo de energia num computador, o software tem também um impacto significativo na energia consumida, pois pode anular, em parte, a eficiência introduzida pelo hardware. Embora Green Computing não seja uma área de investigação nova, o foco tem sido, até recentemente, na componente de hardware. Embora as técnicas de Green Software tenham vindo a evoluir, não há ainda suporte suficiente para que os programadores possam produzir código com consciencialização energética. De facto existemvários estudos que defendem que existe tanto uma falta de conhecimento como uma escassez de ferramentas para o desenvolvimento energeticamente consciente. Esta tese pretende abordar estes dois problemas e tem como foco promover avanços em green software. O tópico do consumo de energia é abordado duma perspectiva de engenharia de software. Através do uso de abordagens sistemáticas, disciplinadas e quantificáveis no processo de desenvolvimento, operação e manutencão de software, foi possível a definição de novas metodologias e ferramentas, apresentadas neste documento. Estas ferramentas e metodologias têm como foco dotar de conhecimento e ferramentas os programadores de software, de modo a suportar um desenvolvimento energeticamente consciente, ou Energyware Engineering. Deste trabalho resulta a compreensão sobre a influência energética a ser usada durante as diferentes fases do processo de desenvolvimento de software. Observamos as linguagens de programação mais populares sobre um ponto de vista de eficiência energética, percebendo quais as mais apropriadas caso o programador tenha uma preocupação com o consumo energético. Apresentamos também um estudo detalhado sobre perfis energéticos de diferentes estruturas de dados em Java, acompanhado por técnicas e ferramentas, fornecendo conhecimento relativo a quais as alternativas energeticamente eficientes que os programadores dispõem. Por forma a ajudar os programadores, definimos e implementamos uma técnica para detetar fragmentos energicamente ineficientes dentro do código fonte de um sistema de software. Esta técnica e ferramenta têm demonstrado ajudar programadores a melhorarem a eficiência energética dos seus programas e em algum casos superando um runtime profiler. Por fim, são dadas respostas a questões e conceções erradamente formuladas dentro desta área de investigação, tais como o relacionamento entre tempo e energia e como é possível melhorar o consumo de energia do software. Foi empregue nesta tese um esforço árduo de suporte tanto na investigação como na educação relativo a este tópico, ajudando à maturação e crescimento de green computing, contribuindo para a resolução da lacuna de conhecimento e ferramentas para suporte a Energyware Engineering.This work is partially funded by FCT – Foundation for Science and Technology, the Portuguese Ministry of Science, Technology and Higher Education, through national funds, and co-financed by the European Social Fund (ESF) through the Operacional Programme for Human Capital (POCH), with scholarship reference SFRH/BD/112733/2015. Additionally, funding was also provided the ERDF – European Regional Development Fund – through the Operational Programmes for Competitiveness and Internationalisation COMPETE and COMPETE 2020, and by the Portuguese Government through FCT project Green Software Lab (ref. POCI-01-0145-FEDER-016718), by the project GreenSSCM - Green Software for Space Missions Control, a project financed by the Innovation Agency, SA, Northern Regional Operational Programme, Financial Incentive Grant Agreement under the Incentive Research and Development System, Project No. 38973, and by the Luso-American Foundation in collaboration with the National Science Foundation with grant FLAD/NSF ref. 300/2015 and ref. 275/2016

Java stream optimization through program fusion

Dissertação de mestrado integrado em Computer ScienceCombining different programs or code fragments is a natural way to build larger programs. This allows programmers to better separate a complex problem into simple parts. Furthermore, by writing programs in a modular way, we increase code reusability. However, these simple parts need to be connected somehow. These connections are done via intermediate structures that communicate results between the different components, harming performance because of the overhead introduced by the allocation and deallocation of multiple structures. Fusion, a very commonly used technique in functional programming, aims to remove the creation of these unnecessary structures, as they don’t take part in the final result. With the introduction of streams and lambda expressions, Java made its way into a more functional programming style. Yet, these mechanisms lack optimization and the adaptation of fusion techniques used by some compilers for functional languages could benefit the performance of Java streams. In this thesis, we study how functional fusion can be adapted to Java Streams.Combinar diferentes programas ou fragmentos de código é uma forma natural de construir programas maiores. Isto permite aos programadores melhor separar um problema complexo em partes simples. Além disso, ao escrever programas de forma modular, estamos a aumentar a reutilização do código. Contudo, estas partes têm de ser ligadas de alguma maneira. Estas conexões são feitas via estruturas intermédias que comunicam os resultados entre os diferentes componentes, prejudicando a performance com o overhead introduzido pela alocação e desalocação de várias estruturas. A fusão, uma técnica muito usada em programação funcional, pretende remover a criação destas estruturas desnecessárias, uma vez que não tomam parte no resultado final. Com a introdução de streams e expressões lambda, o Java abriu caminho para um estilo de programação mais funcional. Mesmo assim, estes mecanismos não possuem otimização e a adaptação de técnicas de fusão utilizadas por alguns compiladores de linguagens funcionais poderiam beneficiar a performance das streams do Java. Nesta dissertação, é estudado como a fusão em programação funcional pode ser adaptada às streams do Java.This work is funded by ERDF - European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation – COMPETE 2020 Programme and by National Funds through the FCT - Foundation for Science and Technology within the project FCOMP-01-0124-FEDER-020484 and grant ref. BI2-2017_PTDC/EEI-ESS/5341/2014_UMINHO

Políticas de Copyright de Publicações Científicas em Repositórios Institucionais: O Caso do INESC TEC

A progressiva transformação das práticas científicas, impulsionada pelo desenvolvimento das novas Tecnologias de Informação e Comunicação (TIC), têm possibilitado aumentar o acesso à informação, caminhando gradualmente para uma abertura do ciclo de pesquisa. Isto permitirá resolver a longo prazo uma adversidade que se tem colocado aos investigadores, que passa pela existência de barreiras que limitam as condições de acesso, sejam estas geográficas ou financeiras. Apesar da produção científica ser dominada, maioritariamente, por grandes editoras comerciais, estando sujeita às regras por estas impostas, o Movimento do Acesso Aberto cuja primeira declaração pública, a Declaração de Budapeste (BOAI), é de 2002, vem propor alterações significativas que beneficiam os autores e os leitores. Este Movimento vem a ganhar importância em Portugal desde 2003, com a constituição do primeiro repositório institucional a nível nacional. Os repositórios institucionais surgiram como uma ferramenta de divulgação da produção científica de uma instituição, com o intuito de permitir abrir aos resultados da investigação, quer antes da publicação e do próprio processo de arbitragem (preprint), quer depois (postprint), e, consequentemente, aumentar a visibilidade do trabalho desenvolvido por um investigador e a respetiva instituição. O estudo apresentado, que passou por uma análise das políticas de copyright das publicações científicas mais relevantes do INESC TEC, permitiu não só perceber que as editoras adotam cada vez mais políticas que possibilitam o auto-arquivo das publicações em repositórios institucionais, como também que existe todo um trabalho de sensibilização a percorrer, não só para os investigadores, como para a instituição e toda a sociedade. A produção de um conjunto de recomendações, que passam pela implementação de uma política institucional que incentive o auto-arquivo das publicações desenvolvidas no âmbito institucional no repositório, serve como mote para uma maior valorização da produção científica do INESC TEC.The progressive transformation of scientific practices, driven by the development of new Information and Communication Technologies (ICT), which made it possible to increase access to information, gradually moving towards an opening of the research cycle. This opening makes it possible to resolve, in the long term, the adversity that has been placed on researchers, which involves the existence of barriers that limit access conditions, whether geographical or financial. Although large commercial publishers predominantly dominate scientific production and subject it to the rules imposed by them, the Open Access movement whose first public declaration, the Budapest Declaration (BOAI), was in 2002, proposes significant changes that benefit the authors and the readers. This Movement has gained importance in Portugal since 2003, with the constitution of the first institutional repository at the national level. Institutional repositories have emerged as a tool for disseminating the scientific production of an institution to open the results of the research, both before publication and the preprint process and postprint, increase the visibility of work done by an investigator and his or her institution. The present study, which underwent an analysis of the copyright policies of INESC TEC most relevant scientific publications, allowed not only to realize that publishers are increasingly adopting policies that make it possible to self-archive publications in institutional repositories, all the work of raising awareness, not only for researchers but also for the institution and the whole society. The production of a set of recommendations, which go through the implementation of an institutional policy that encourages the self-archiving of the publications developed in the institutional scope in the repository, serves as a motto for a greater appreciation of the scientific production of INESC TEC