Debugging Cyber-Physical Systems with Pharo

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 have been introduced. Amongst them, online debuggers provide 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 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 out-of-place debugging. The goal is to minimize the debugging interference characteristic of online debugging while allowing online remote capabilities. An out-of-place debugger transfers the program execution and application state from the debugged application to the debugger application, each running in a different process.Knowledge On the one hand, out-of-place 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 running several benchmarks, comparing our approach with a classic remote online debugger. We show that our prototype debugger outperforms a traditional remote debugger by 1000 times 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. ACM CCS 2012Software and its engineering → Software testing and debugging;

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“…In what follows we discuss the debugging experience of IDRA and TelePharo. Further details on the case study can be found in [24].…”

Section: Resultsmentioning

confidence: 99%

“…Following Pacheco [30] and the survey from McDowell and Helmbold [25], we categorize debugging techniques in two big families: Offline Debugging and Online Debugging. 3 More information about the CPS application and its deployment can be found in [24].…”

Section: Online and Offline Debuggingmentioning

confidence: 99%

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

2018

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“…In regards to the original use-case [9], Collectors provided dynamic and non-intrusive instrumentations to observe the runtime. We use remote debuggers as a support to remotely control Collectors and get feedback from the collected objects.…”

Section: Discussionmentioning

confidence: 99%

“…As an illustration, we used the Sensor Monitoring Application usecase [9]. It is a single threaded Pharo IOT application deployed on a Raspberry Pi 2 in which there is an unpredictable bug at runtime.…”

Section: The Sensor Monitoring Application Usecasementioning

confidence: 99%

Collectors

Costiou

Kerboeuf

Plantec

et al. 2018

Conference Companion of the 2nd International Conference on Art, Science, and Engineering of Programming

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“…The developer proceeds then to debug as if the application was originally a local application. In previous work, we successfully applied this approach to debugging long-running applications and cyber-physical systems [18,16]. Such a debugging technique suits Big Data applications since it allows production code running on a cluster to continue processing tasks while the failing tasks can be debugged in an external machine.…”

Section: Online Debugging Of Big Data Applicationsmentioning

confidence: 99%