Lightweight monitoring of transactional memory programs

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Transactional failure recovery for a distributed key-value store

With the advent of cloud computing, many applications have embraced the ensuing paradigm shift towards modern distributed key-value data stores, like HBase, in order to benefit from the elastic scalability on offer. However, many applications still hesitate to make the leap from the traditional relational database model simply because they cannot compromise on the standard transactional guarantees of atomicity, isolation, and durability. To get the best of both worlds, one option is to integrate an independent transaction management component with a distributed key-value store. In this paper, we discuss the implications of this approach for durability. In particular, if the transaction manager provides durability (e.g., through logging), then we can relax durability constraints in the key-value store. However, if a component fails (e.g., a client or a key-value server), then we need a coordinated recovery procedure to ensure that commits are persisted correctly. In our research, we integrate an independent transaction manager with HBase. Our main contribution is a failure recovery middleware for the integrated system, which tracks the progress of each commit as it is flushed down by the client and persisted within HBase, so that we can recover reliably from failures. During recovery, commits that were interrupted by the failure are replayed from the transaction management log. Importantly, the recovery process does not interrupt transaction processing on the available servers. Using a benchmark, we evaluate the impact of component failure, and subsequent recovery, on application performance.

Residuals for log-Burr XII regression models in survival analysis

In this paper, we compare three residuals to assess departures from the error assumptions as well as to detect outlying observations in log-Burr XII regression models with censored observations. These residuals can also be used for the log-logistic regression model, which is a special case of the log-Burr XII regression model. For different parameter settings, sample sizes and censoring percentages, various simulation studies are performed and the empirical distribution of each residual is displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be straightforwardly extended to the modified martingale-type residual in log-Burr XII regression models with censored data.

A log-extended Weibull regression model

A bathtub-shaped failure rate function is very useful in survival analysis and reliability studies. The well-known lifetime distributions do not have this property. For the first time, we propose a location-scale regression model based on the logarithm of an extended Weibull distribution which has the ability to deal with bathtub-shaped failure rate functions. We use the method of maximum likelihood to estimate the model parameters and some inferential procedures are presented. We reanalyze a real data set under the new model and the log-modified Weibull regression model. We perform a model check based on martingale-type residuals and generated envelopes and the statistics AIC and BIC to select appropriate models. (C) 2009 Elsevier B.V. All rights reserved.

The generalized log-gamma mixture model with covariates: local influence and residual analysis

In a sample of censored survival times, the presence of an immune proportion of individuals who are not subject to death, failure or relapse, may be indicated by a relatively high number of individuals with large censored survival times. In this paper the generalized log-gamma model is modified for the possibility that long-term survivors may be present in the data. The model attempts to separately estimate the effects of covariates on the surviving fraction, that is, the proportion of the population for which the event never occurs. The logistic function is used for the regression model of the surviving fraction. Inference for the model parameters is considered via maximum likelihood. Some influence methods, such as the local influence and total local influence of an individual are derived, analyzed and discussed. Finally, a data set from the medical area is analyzed under the log-gamma generalized mixture model. A residual analysis is performed in order to select an appropriate model.

Log-modified Weibull regression models with censored data: Sensitivity and residual analysis

This paper proposes a regression model considering the modified Weibull distribution. This distribution can be used to model bathtub-shaped failure rate functions. Assuming censored data, we consider maximum likelihood and Jackknife estimators for the parameters of the model. We derive the appropriate matrices for assessing local influence on the parameter estimates under different perturbation schemes and we also present some ways to perform global influence. Besides, for different parameter settings, sample sizes and censoring percentages, various simulations are performed and the empirical distribution of the modified deviance residual is displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be straightforwardly extended for a martingale-type residual in log-modified Weibull regression models with censored data. Finally, we analyze a real data set under log-modified Weibull regression models. A diagnostic analysis and a model checking based on the modified deviance residual are performed to select appropriate models. (c) 2008 Elsevier B.V. All rights reserved.

A Log-Linear Regression Model for the Beta-Weibull Distribution

We introduce the log-beta Weibull regression model based on the beta Weibull distribution (Famoye et al., 2005; Lee et al., 2007). We derive expansions for the moment generating function which do not depend on complicated functions. The new regression model represents a parametric family of models that includes as sub-models several widely known regression models that can be applied to censored survival data. We employ a frequentist analysis, a jackknife estimator, and a parametric bootstrap for the parameters of the proposed model. We derive the appropriate matrices for assessing local influences on the parameter estimates under different perturbation schemes and present some ways to assess global influences. Further, for different parameter settings, sample sizes, and censoring percentages, several simulations are performed. In addition, the empirical distribution of some modified residuals are displayed and compared with the standard normal distribution. These studies suggest that the residual analysis usually performed in normal linear regression models can be extended to a modified deviance residual in the proposed regression model applied to censored data. We define martingale and deviance residuals to evaluate the model assumptions. The extended regression model is very useful for the analysis of real data and could give more realistic fits than other special regression models.

Sudden onset of log-periodicity and superdiffusion in non-Markovian random walks with amnestically induced persistence: exact results

Random walks can undergo transitions from normal diffusion to anomalous diffusion as some relevant parameter varies, for instance the L,vy index in L,vy flights. Here we derive the Fokker-Planck equation for a two-parameter family of non-Markovian random walks with amnestically induced persistence. We investigate two distinct transitions: one order parameter quantifies log-periodicity and discrete scale invariance in the first moment of the propagator, whereas the second order parameter, known as the Hurst exponent, describes the growth of the second moment. We report numerical and analytical results for six critical exponents, which together completely characterize the properties of the transitions. We find that the critical exponents related to the diffusion-superdiffusion transition are identical in the positive feedback and negative feedback branches of the critical line, even though the former leads to classical superdiffusion whereas the latter gives rise to log-periodic superdiffusion.

Sistema de Controle log??stico de Medicamentos Antirretrovirais (SICLOM)

O Sistema de Controle Log??stico de Medicamentos Antirretrovirais (Siclom) ?? uma ferramenta criada com o objetivo de gerenciamento log??stico dos medicamentos antirretrovirais (ARV) e de aprimoramento da qualifica????o da dispensa????o. Esse sistema permite que o departamento de DST, Aids e Hepatites Virais, secretarias estaduais e municipais de Sa??de mantenham-se atualizados em rela????o ao fornecimento, dispensa????o de medicamentos aos pacientes em tratamento conforme as recomenda????es existentes no Consenso Terap??utico Brasileiro, al??m do controle dos estoques de cada medicamento nas v??rias regi??es do pa??s. As informa????es de consumo e estoques s??o fundamentais para que o adequado suprimento aos estados ocorra evitando, assim, a ruptura dos estoques locais e preju??zo no atendimento aos pacientes. Atualmente utilizam o sistema 670 unidades dispensadoras de medicamentos, distribu??das em todo o Brasil; 27 coordena????es estaduais de DST/Aids; 61 almoxarifados; e 936 maternidades

Log??stica de distribui????o e entrega dos objetos do Programa Nacional do Livro Did??tico (PNLD)

O Programa Nacional do Livro Did??tico ??? PNLD, administrado pelo Fundo Nacional de Desenvolvimento da Educa????o ??? FNDE, utiliza, desde 1994, os servi??os da Empresa Brasileira de Correios e Tel??grafos - ECT, para levar ??s escolas p??blicas mais de uma centena de milh??es de livros did??ticos. V??rios eram os problemas a serem resolvidos. Antes de a ECT assumir os servi??os, somente 25% dos livros eram entregues antes do in??cio do ano letivo e o restante entregue durante ano, prejudicando de uma sobre maneira, n??o s?? alunos e professores, mas todo o planejamento de ensino. A aus??ncia de um controle efetivo da entrega dos livros, aliado ao endere??amento incorreto, gerava um de alto ??ndice de reclama????o quanto ao n??o recebimento dos objetos. Com as a????es descritas nesse relato, foi poss??vel aumentar o n??mero de crian??as/adolescentes estudantes de escolas p??blicas, com cobertura de todos os munic??pios brasileiros, os quais s??o na realidade os grandes clientes de todo o processo. Certamente que o sucesso da opera????o envolve a FNDE e a ECT, sendo que nesta ??ltima ?? imprescind??vel a perfeita sintonia entre todas as ??reas

Cataloga????o, uma ferramenta para a log??stica

A cataloga????o consiste numa ferramenta de aplica????o nos ??rg??os p??blicos federais, que permite o uso de linguagem ??nica de identifica????o de materiais, de forma que possa ser entendida e manipulada por qualquer sistema, desde que este conhe??a as regras da linguagem. Essa ferramenta, entre outras utilidades, possibilita a execu????o de boa gest??o de material, por meio da intera????o de todos os ??rg??os do governo, permitindo o apoio m??tuo entre eles, e da nacionaliza????o de itens importados, contribuindo para a redu????o de nossa depend??ncia externa e para o incentivo ?? ind??stria nacional. A cataloga????o possibilita, ainda, a descoberta de utiliza????o de itens comuns de material, a perfeita identifica????o de um item, a otimiza????o do planejamento or??ament??rio e a redu????o do custo log??stico dos ??rg??os por melhor compra, armazenagem, aplica????o, destina????o de excessos e otimiza????o de estoques

Sistema de avalia????o log??stica variada

As normas que regem a gratifica????o de Desempenho e Produtividade ??? GDP ??? recebidas pelos servidores da Carreira de Finan??as e Controle da Secretaria Federal de Controle, estabelecem limites pares ao n??mero de servidores que podem ser avaliados com notas superiores a 8. Essa limita????o est?? fixada em 20% para as notas na faixa de 8 a 9 e 10% para as notas acima de 9. O fato da Secretaria Federal de Controle possuir muitas unidades, inviabilizou a escolha dos servidores que, devido ao seu melhor desempenho, mereceriam receber as notas mais altas. A solu????o deste e de outros problemas dele decorrentes foi a implementa????o do Sistema de Avalia????o Log??stica Variada ??? SALVA, que operacionaliza a distribui????o dos valores n??o inteiros da gratifica????o de desempenho e produtividade com exatid??o e igualdade

M??dulo 1 - a import??ncia e a necessidade da lei de licita????es: curso legisla????o aplicada ?? log??stica de suprimentos lei 8.666/93, preg??o e registro de pre??os

Este documento trata de: aspectos conceituais da lei: finalidade, import??ncia e hierarquia da lei.; no????es gerais da lei de licita????es - Lei n?? 8.666/93; tipos de licita????o:menor pre??o, melhor t??cnica, t??cnica e pre??o e maior lance ou oferta; modalidades de licita????o: concorr??ncia, tomada de pre??os, convite, concurso e leil??o; exce????es ?? obrigatoriedade de licita????o: dispensa e inexigibilidade; regime de execu????o indireta; comiss??o de licita????o; etapas do processo licitat??rio: edital, procedimentos/documentos do certame, registro cadastral, habilita????o dos interessados, julgamento e encerramento; preg??o; registro de pre??os