Out-Of-Place debugging: a debugging architecture to reduce debugging interference

Context. Recent studies show that developers spend most of their programming time testing, verifying and debugging software. As applications become more and more complex, developers demand more advanced debugging support to ease the software development process. Inquiry. Since the 70's many debugging solutions were introduced. Amongst them, online debuggers provide a good insight on the conditions that led to a bug, allowing inspection and interaction with the variables of the program. However, most of the online debugging solutions introduce \textit{debugging interference} to the execution of the program, i.e. pauses, latency, and evaluation of code containing side-effects. Approach. This paper investigates a novel debugging technique called \outofplace debugging. The goal is to minimize the debugging interference characteristic of online debugging while allowing online remote capabilities. An \outofplace debugger transfers the program execution and application state from the debugged application to the debugger application, both running in different processes. Knowledge. On the one hand, \outofplace debugging allows developers to debug applications remotely, overcoming the need of physical access to the machine where the debugged application is running. On the other hand, debugging happens locally on the remote machine avoiding latency. That makes it suitable to be deployed on a distributed system and handle the debugging of several processes running in parallel. Grounding. We implemented a concrete out-of-place debugger for the Pharo Smalltalk programming language. We show that our approach is practical by performing several benchmarks, comparing our approach with a classic remote online debugger. We show that our prototype debugger outperforms by a 1000 times a traditional remote debugger in several scenarios. Moreover, we show that the presence of our debugger does not impact the overall performance of an application. Importance. This work combines remote debugging with the debugging experience of a local online debugger. Out-of-place debugging is the first online debugging technique that can minimize debugging interference while debugging a remote application. Yet, it still keeps the benefits of online debugging ( e.g. step-by-step execution). This makes the technique suitable for modern applications which are increasingly parallel, distributed and reactive to streams of data from various sources like sensors, UI, network, etc

Prove su tavola vibrante di un silo metallico a fondo piano: identificazione dinamica mediante accelerometri

La tesi descrive le metodologie messe in atto al fine di interpretare il comportamento di un silo metallico a fondo piano, contenente grano, soggetto a vari input sismici: segnali di tipo random (white noise), sinusoidi a bassa frequenza, ed accelerogrammi corrispondenti a sismi reali e artificiali (selezionati e costruiti in modo da avere determinati contributi in frequenza), opportunamente scalati in relazione alla risposta strutturale. Vengono quindi analizzati i risultati di estensimetri (strain gauges), accelerometri (monoassiali) e celle di pressione, effettuando confronti, oltre che tra le due configurazioni strutturali, anche tra le varie teorie (Eurocodice , Silvestri et al 2012 e Pieraccini et al 2015). Vengono ricavati due tipologie di grafici utili alla comprensione del complesso meccanismo resistente: l'andamento delle sovrappressioni dinamiche con l'accelerazione e l'andamento dello sforzo normale nei montanti con l'accelerazione. I risultati in configurazione isolata vengono inoltre confrontati con le previsioni di modelli ad 1 e 2 gradi di libertà, lineari (considerando le proprietà equivalenti dell'isolatore) e non lineari (considerando l'effettivo diagramma costitutivo forza-spostamento dell'isolatore). Centrale risulta l'analisi dei segnali degli accelerometri, volte principalmente all'identificazione dinamica sperimentale (incrociando informazioni di frequenza e fase, correlazione, cross-correlazione, densità di potenza) mediante il metodo dei punti di mezza potenza che permette di determinare il periodo fondamentale, il rapporto di smorzamento modale e la forma modale. È da sottolineare, infine, il fatto che questa tesi, insieme ad altre, rappresenta solamente l'inizio del processo di interpretazione dei risultati, considerata la mole di dati ottenuta nei test effettuati (256 in totale)

Local Propagation in Constraint-based Neural Network

In this paper we study a constraint-based representation of neural network architectures. We cast the learning problem in the Lagrangian framework and we investigate a simple optimization procedure that is well suited to fulfil the so-called architectural constraints, learning from the available supervisions. The computational structure of the proposed Local Propagation (LP) algorithm is based on the search for saddle points in the adjoint space composed of weights, neural outputs, and Lagrange multipliers. All the updates of the model variables are locally performed, so that LP is fully parallelizable over the neural units, circumventing the classic problem of gradient vanishing in deep networks. The implementation of popular neural models is described in the context of LP, together with those conditions that trace a natural connection with Backpropagation. We also investigate the setting in which we tolerate bounded violations of the architectural constraints, and we provide experimental evidence that LP is a feasible approach to train shallow and deep networks, opening the road to further investigations on more complex architectures, easily describable by constraints

Longitudinal case study of the role of libero in volleyball

In volleyball, the role of libero is highly specialized compared to the others, thanks to high abilities in the individual fundamental of the Bagher and in the team fundamentals of reception and defence. Therefore, coaches are committed to differentiate training programs from those of the remaining team members and this also affects the checks: in fact, results will have a greater weight compared to the same efficacy measurements of the fundamental of the Bagher of other roles. It’s therefore very useful to monitor, through a series of tests, the work done in the gym: results will help to recalibrate the training plan to combine team goals with needs of the libero. The purpose of this study is to monitor the level of efficacy of the individual fundamental of the Bagher, employed in the following moments of game: free-ball; service receiving; spike defence. To do this, the tests were: Bagher of free-ball in zone 5; receiving Bagher in zone 1 and in zone 6; defence Bagher in zone 5. The method is experimental longitudinal and consists in detecting the initial and final data in a period of time of 8 months for the technical ability in the aforementioned fundamental of a player in the role of libero in series B1. From the results, it comes out that the training activities are constantly monitored and the purpose can be considered achieved, because the coach has verified the athlete's performance level over time noting a final performance improvement, also confirmed by the game-data

Study on the enabling capacity in the individual roles of basic competitive volleyball

Testing is used to measure the performance and, therefore, to check for the improvements resulting from training activity. More and more frequently, coaches require checks even during the current sporting season to measure the state of the athletes' performance and possibly change their training plans in order to make them more effective. Increasingly testing also has a monitoring function and, therefore, it is expected in the ordinary training activities without changing the annual planning. To do this, it is necessary to provide a type of functional tests for training. The purpose of this study is to monitor the state of efficacy of individual volleyball fundamental of a basic competitive level

The “direct five-step procedure” for the design of added viscous dampers to be inserted into existing buildings: formulation and case study

This paper introduces an updated formulation of a five-step procedure dealing with the design of fluid viscous dampers for the seismic retrofitting of existing frame buildings. The original design procedure is known as the “direct five-step procedure,” and is articulated into 5 consecutive steps guiding the designer from the identification of the expected seismic performances, to the sizing of the added viscous dampers up to the final verification of the seismic behavior through non-linear dynamic time history analyses. The procedure leads to the full definition of the mechanical characteristics of the commercial non-linear viscous dampers and allows to estimate the maximum dissipative forces acting in the dampers and the internal forces in the frame members. The objective of the design procedure, when applied to a new building, is to size the dampers in order to keep the structural elements within the linear elastic range considering a “rare” earthquake design level. However, when dealing with an existing building, especially if originally designed considering vertical loads only, the insertion of viscous dampers could be not sufficient to keep the structural elements in the elastic range. Thus, it might be necessary to accept local plastic excursion of the structural elements, by taking into account the ductility capacity (albeit probably limited) of the structural members (hysteretic dissipation associated with damage in beams and columns). This latter aspect is explicitly considered in the updated formulation of the “direct five-step procedure” presented here through the introduction of an overall response reduction factor accounting for both the ductility capacity of the structural members and the viscous damping provided by the added dampers. The design procedure is then applied to a 11-storey frame structure case study, which is representative of reinforced concrete buildings designed for vertical loads only. Three different retrofitting design strategies are considered, based on different exploitation of viscous energy dissipation provided by the dampers and hysteretic energy dissipation due to the excursion of the structural members into the inelastic regime

Use of tranexamic acid in total knee arthroplasty

PURPOSE: different strategies have been developed to reduce blood loss in total knee arthroplasty (TKA). The efficacy of both systemic and local tranexamic acid (TXA) administration is demonstrated in the literature. The aim of the present study was to compare the efficacy of systemic, local and combined (systemic + local) administration of TXA in reducing blood loss after TKA. METHODS: we enrolled all patients submitted to a primary TKA in our department between November 2014 and August 2015. They were divided into three groups corresponding to the method of TXA administration used: intravenous (IV), intra-articular (IA), and a combination of the two. Demographic data, as well as preoperative hemoglobin and platelet levels, were collected. The primary outcome was the maximum hemoglobin loss, while the secondary outcomes were the amount of blood in the drain (cc/hour) and the rate of transfusions; postoperative pain was also assessed. Student’s t-test or a χ(2) test was used to evaluate between-group differences, using p<0.05 as the cut-off for statistically significant differences. RESULTS: the sample comprised 34 patients: IV, 10 cases; IA, 15 cases, and combined (IV + IA), 9 cases. The average age of the patients was 71.1±6.4 years. No significant differences in the outcome measures were found between the groups, with the exception of a significantly lower maximum hemoglobin loss in the combined versus the IV group (p=0.02). There were no differences between the groups in the amount of blood in the drain or the rate of transfusions. CONCLUSIONS: the data from this preliminary study, as well as data from the literature, confirm that TXA administration is safe and effective in reducing total blood loss in TKA, and no administration protocol seems to be superior to the others. LEVEL OF EVIDENCE: Level II, prospective comparative study

A debugging approach for live Big Data applications

International audienceMany frameworks exist for programmers to develop and deploy Big Data applications such as Hadoop Map/Reduce and Apache Spark. However, very little debugging support is currently provided in those frameworks. When an error occurs, developers are lost in trying to understand what has happened from the information provided in log files. Recently, new solutions allow developers to record & replay the application execution, but replaying is not always affordable when hours of computation need to be re-executed. In this paper, we present an online approach that allows developers to debug Big Data applications in isolation by moving the debugging session to an external process when a halting point is reached. We introduce IDRA MR , our prototype implementation in Pharo. IDRA MR centralizes the debugging of parallel applications by introducing novel debugging concepts, such as composite debugging events, and the ability to dynamically update both the code of the debugged application and the same configuration of the running framework. We validate our approach by debugging both application and configuration failures for two driving scenarios. The scenarios are implemented and executed using Port, our Map/Reduce framework for Pharo, also introduced in this paper