Concurrent programs

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Structural testing criteria for concurrent programs considering loop execution

Structural testing criteria for concurrent programs considering loop execution

conditions are required to trigger a concurrency error (how many threads, variables, accesses, etc). ( LU et al. , 2008 ) makes emphasis in that real world concurrency errors are not proven or tested, given that it is very difficult to characterize them and it is time-consuming to report them due to non-determinism and therefore difficult replication. Also, concurrent programs are more difficult to understand. The bug characteristics found in ( LU et al. , 2008 ) are strongly linked to their methodology and to the programs they selected: real large applications such as Open Office, Apache, Mozilla and MySQL. Authors take the database of reported errors and look for those related to concurrency. It can also be limited to client-server and C applications, since apps in Java or operating systems were not examined. ( LU et al. , 2008 ) presents characteristics and categories regarding the pattern of errors, manifestation of errors and correction of errors. ( LU et al. , 2008 ) separates two types of bugs: deadlock and non-deadlock bugs. Data race is not classified as a pattern since there also exist "benign" data races. Most errors are manifested by interactions between two or a small group of threads, because they usually do not interact closely with others. Some of the deadlock errors are manifested with a single thread, which is when trying to acquire a resource taken by itself. ( LU et al. , 2008 ) points out that the study can contribute to the definition of criteria, based on the characteristics of the manifestation of bugs. ( Farchi; Nir; Ur , 2003 ) defines two types of bug patterns: those that are generated when a design pattern is implemented and when an anti-design pattern is implemented. There are three categories defined:
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Understanding the energy Behavior of concurrent haskell programs

Understanding the energy Behavior of concurrent haskell programs

Energy-efficiency has concerned hardware and low-level software designers for years. However, the rapid proliferation of battery-powered mobile devices combined with the growing worldwide movement towards sustainability have caused developers and researchers to study the energy impact of application software in execution. Recent work has studied the effect that factors such as code obfuscation, object-oriented refactorings, and data types have on energy efficiency. In this work, we attempt to shed light on the energy behavior of concurrent programs written in a purely functional language, Haskell. We conducted an empirical study to assess the performance and energy behavior of three different thread management approaches and three primitives for concurrency control using nine different benchmarks with an experimental space exploration of more than 400 configurations. In this study, we found out that small changes can make a big difference in terms of energy consumption. For instance, in one of our benchmarks, under a specific configuration, choosing one concurrency control primitive (MVar) over another (TMVar) can yield 60% energy savings. Also, the relationship between energy consumption and performance is not always clear. We found scenarios where the configuration with the best performance also exhibited the worst energy consumption. To support developers in better understanding this complex relationship, we have extended two existing performance analysis tools also to collect and present data about energy consumption. In addition, based on the results of our empirical study, we provide a list of guidelines for developers with good practices for writing energy-efficient code in this environment.
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Proving concurrent constraint programming correct, revisited

Proving concurrent constraint programming correct, revisited

Reasoning about concurrent programs is much harder than reasoning about se- quential ones. Programmers often find themselves overwhelmed by the many subtle cases of thread interactions they must be aware of to decide whether a concurrent program is correct or not, and by the need of finding the right level of thread atomic- ity of concurrent programs, avoiding race conditions, coping with mutual exclusion requirements, and guaranteeing deadlock freeness to ensure program reliability.

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Type-based Protocol Conformance and Aliasing Control in Concurrent Java Programs

Type-based Protocol Conformance and Aliasing Control in Concurrent Java Programs

In an object-oriented setting, objects are modeled by their state and operations. The pro- grammer should be aware of how each operation implicitly changes the state of an object. This is due to the fact that in certain states some operations might not be available, e.g., reading from a file when it is closed. Additional care must be taken if we consider alias- ing, since many references to the same object might be held and manipulated. This hin- ders the ability to identify the source of a modification to an object, thus making it harder to track down its state. These difficulties increase in a concurrent setting, due to the un- predictability of the behavior of concurrent programs. Many of the errors that appear in such programs are due to inconsistent states caused by unrestricted concurrent access to shared memory. Building robust and correct concurrent applications requires advanced knowledge of concurrency control mechanisms and, even then, over-conservative solu- tions might be used, e.g., synchronization on an entire method instead of applying a finer grained synchronization technique that protects critical regions of the code.
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A Tutorial on Parallel and Concurrent Programming in Haskell

A Tutorial on Parallel and Concurrent Programming in Haskell

Writing semi-implicitly parallel programs can sometimes help to parallelize pure functional programs but it does not work when we want to parallelize stateful computations in the IO monad. For that we need to write explicitly threaded programs. In this section we introduce Haskell’s mechanisms for writing explic- itly concurrent programs. Haskell presents explicit concurrency features to the programmer via a collection of library functions rather than adding special syn- tactic support for concurrency and all the functions presented in this section are exported by this module.
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Linear and shared objects in concurrent programming

Linear and shared objects in concurrent programming

Mainstream object-oriented languages, like Java, can automatically detect and pre- vent (standard) type and initialisation errors through compile-time checks. However, they cannot detect and prevent errors related to usage protocols (usually only described in informal documentation), which end up revealing themselves as runtime exceptions in languages equipped with built-in support to handle errors and exceptional events. For example, reading from a file should follow the rules of a well-known usage protocol: first a file must be opened, then it can be read multiple times (without reading beyond the end-of-file), and finally it must be closed. Nevertheless, in mainstream object-oriented languages, any disregard of this specification is only detected when it eventually causes a runtime exception. As a result, one of the major topics of computer science today is the study of strategies that can verify sequential and concurrent programs against precise interface specifications.
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Concurrent object-oriented programming: The MP-Eiffel approach

Concurrent object-oriented programming: The MP-Eiffel approach

happens with Actor languages and SCOOP ). However, if that is not the case, then that choice is not so clear. The question here is not whether objects communi- cate through message passing (which they always do), but which processor has the responsibility to fulfill the request executing the appropriate feature. If a concur- rent program is seen as the aggregation of communicating sequential programs (one for each processor) using shared resources, then the simplest solution will be the shared memory model. As will be seen, from this choice results also a simpler and more efficient integration of the exception handling mechanism with concurrency. Nevertheless, as mentioned previously, the usefulness of a direct inter-processor com- munication mechanism, as exists in Actors or SCOOP , is obvious. It is useful, for example, to implement client-server program architectures, or for loosely connected distributed systems.
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Admission Criteria for MBA Programs

Admission Criteria for MBA Programs

An argument against the use of labor variables in MBA selection processes is the lack of generalized measurement criteria. This poses two challenges: (a) comparing the results of different studies and (b) explaining why these variables effects are not always significant. This is a major reason for not including this category of variables in the present review. Although it is included in a considerable number of studies, the variety of conceptual and operational definitions impeded to construct an equivalent data set. Even though the number of years of work experience is a commonly used variable, its definition differs in many studies: Some studies refer to the entire working career, whereas others consider only jobs “relevant” for MBA programs, in rather arbitrary terms or according to diverse quantitative or qualitative criteria.
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Concurrent architecture for control of an autonomous driving vehicle

Concurrent architecture for control of an autonomous driving vehicle

Seven different type of processes were defined: image capturing, image visualization and recording, road image processing, sign image processing, perception (Road analysis), agent (decis[r]

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Hormonal responses and oxygen uptake in concurrent training

Hormonal responses and oxygen uptake in concurrent training

supports what we stated in the lines above and confirmed what Di Blasio et al. (2012) have found in women, i.e. the RE scheduling elicited the lowest EPOC respect to ER and AERE scheduling. Remembering the workouts data, i.e. the fact that the experimented workouts did not elicited a different relative and absolute VO2, VCO2, HR, RER and F, a possible explanation of our post-exercise results could be furnished not only by the hypothetical negative impact of the increased protein utilization on metabolism, but also by Lundberg, Fernandez-Gonzalo, Tesch, Rullman, and Gustafsson (2016) findings. They found that aerobic exercise may boost the hypertrophic response to short-term resistance training. Indeed they explored the effects of an acute aerobic exercise session on the transcriptional response to subsequent resistance exercise session having similar characteristics of our exercise protocols. They found that an exhaustive aerobic exercise insult is able to alter the skeletal muscle transcriptional signature of resistance exercise to initiate important gene programs, promoting both myofiber growth and improved oxidative capacity, when performed prior to resistance exercise.
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Non-Blocking Concurrent Imperative Programming with Session Types

Non-Blocking Concurrent Imperative Programming with Session Types

This chapter introduces the main concepts of programming with Concurrent C0 (CC0). For a more in-depth description of CC0, we refer the reader to the original paper [30]. C0 [21] is an imperative programming language, closely resembling C, with the goal of having fully specified semantics that avoid C’s undefined behaviour [1]. It is used in Carnegie Mellon University to learn the basics of imperative algorithms and data structures and compiler design. Its main features are: dynamically checked contracts (for example, @requires, @ensures, @asserts and @loop_invariant ); complete memory distinction by separating pointers from arrays; and a garbage collector, which eliminates the need to free memory. C0 is compiled to C, generating human-readable code that is sent to a C compiler.
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APRESENTAÇÃO_Sustainable food security programs

APRESENTAÇÃO_Sustainable food security programs

• 2) Smallholders manage over 80 per cent of the world’s estimated 500 million small farms and provide over 80 per cent of the food consumed in a large part of the developing world, [r]

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Rewriting Concurrent Haskell programs to STM

Rewriting Concurrent Haskell programs to STM

Luff (2009) executed an experiment with a sample of 17 students, approaching the use of STM, Actor Model and locking in Java while collecting data on solutions’ size and development time. He also surveyed his subjects regarding their impressions. Only a subjective preference for STM over locking was found significant. Nevertheless, the results could be more statistically significant had the subjects’ sample size been bigger. Rossbach et al. (2010) examined over 1000 implementations of a concurrent simulation developed by three groups of undergraduate students. They cover concurrent programming using coarse- and fine-grained locking, condition-based synchronization, and transactions. Their study reports more mistakes using fine-grained locking than STM, while coarse-grained locking and STM present common error patterns. However, this study has some methodological problems (Pankratius and Adl-Tabatabai, 2011), such as first year students using a different STM implementation and students assigning themselves to groups. On the other hand, Pankratius and Adl-Tabatabai (2011) organized six pairs of graduate students to develop a parallel search engine. Three used STM and the other three employed locks. The authors found out that TM pairs were among the first to have a prototype, spent less time debugging segmentation faults, and produced code that is easier to understand. Even though it presents interesting lessons, more data would be expected for such strong claims.
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Criteria for HIV screening programs

Criteria for HIV screening programs

Since there is no effective treatment for HIV infections, the public health ration- ale for HIV screening programs rests on the premise that identifying infected [r]

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Murine typhus control programs

Murine typhus control programs

The expectation, if DDT is successful in controllmg typhus, is first a reduction in rat fleas and other ectoparasites, second a drop in typhus infection among the ra[r]

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BREEDING PROGRAMS AND TARGETS

BREEDING PROGRAMS AND TARGETS

ABSTRACT - Brazil has the largest commercial beef cattle herd and is the main beef exporter in the world. Cultivated pastures are the basis for the Brazilian beef production, and occupy an area of 101.4 million hectares. However, very few forage cultivars are commercially available, and the majority of these are of apomictic reproduction, thus genetically homogeneous. Tropical forage breeding is at its infancy, but much investment and efforts have been applied in the last three decades and some new cultivars have been released. In this paper, origin of different species, modes of reproduction, breeding programs and targets are discussed and the resulting new cultivars released are presented.
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Universidade Estadual de Campinas. CVS - Concurrent Version System

Universidade Estadual de Campinas. CVS - Concurrent Version System

 Comandos do CVS são utilizados para acessar o repositório e gerar cópias em um diretório de trabalho..  Usar os comandos do CVS para enviar as mudanças do diretório de trabalho para o[r]

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EM4596 Repeater Concurrent Dual Band WiFi AC1200

EM4596 Repeater Concurrent Dual Band WiFi AC1200

Se não tiver um modem/router de Banda Dupla, pode atualizar a sua rede Wi-Fi utilizando o EM4596 para criar uma rede Wi-Fi de Banda Dupla.. O EM4596 será ligado à sua ligação de 2.4GHz[r]

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Boosting State Machine Replication with Concurrent Execution

Boosting State Machine Replication with Concurrent Execution

Modern multi-processor servers challenge the state machine replication model since deterministic execution of requests often leads to single-threaded replicas. To overcome this limitation, a number of techniques have been proposed to allow multi-threaded execution of requests in state machine replication (e.g., [1], [2], [11], [17], [18], [25]). Most existing techniques build on the observation that independent requests can execute concurrently while conflicting requests must be serialized and executed in the same order by the replicas—two requests conflict if they access common state and at least one of them updates the state, otherwise requests are independent. Existing proposals differ on how dependency-based schedul- ing is performed to provide concurrent execution of inde-
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Identification and analyzes of concurrent multiple nucleotide substitutions

Identification and analyzes of concurrent multiple nucleotide substitutions

This thesis focuses on the identification of concurrent MNS from polymorphic variation in five human genes (BRCA1, LDLR, LRRK2, PSEN1, RET). Our analyses resulted in a total of 43 clusters with representative examples of distinct concurrent MNS (Tandem Base Mutations, Complex MNS and Noncontiguous MNS). Patterns of double, triple and more than three mutations were detected and analyzed. Other studies were performed such as what concerns the population specificity and the existence of a preference in the type of nucleotide substitution.The major outcome was the observation of a significant difference in the transition/transversion rate (RTs/Tv) between TBS and Noncontiguous MNS, which is independent of distance between mutations.
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