FADI: a fault-tolerant environment for open distributed computing

FADI is a complete programming environment that serves the reliable execution of distributed application programs. FADI encompasses all aspects of modern fault-tolerant distributed computing. The built-in user-transparent error detection mechanism covers processor node crashes and hardware transient failures. The mechanism also integrates user-assisted error checks into the system failure model. The nucleus non-blocking checkpointing mechanism combined with a novel selective message logging technique delivers an efficient, low-overhead backup and recovery mechanism for distributed processes. FADI also provides means for remote automatic process allocation on the distributed system nodes

Accommodating a High Penetration of PHEVs and PV Electricity in Residential Distribution Systems

Global warming is threatening the world’s delicate ecosystems to the point where the extinction of numerous species is becoming increasingly likely. Experts have determined that avoiding such a disaster requires an 80% reduction in the 1990 levels of global greenhouse gas emissions by 2050. The problem has been exacerbated by the booming demand for electrical energy. This situation creates a complex dilemma: on the one hand, energy sector emissions must be decreased; on the other, electrical energy production must be increased to meet the growing demand. The use of renewable emission-free sources of electrical energy offers a feasible solution to this dilemma. Solar energy in particular, if properly utilized, would be an effective means of meeting worldwide electricity needs. Another viable component of the solution is to replace gasoline-powered vehicles with plug-in hybrid electric vehicles (PHEVs) because of their potential for significantly reducing greenhouse gas emissions from the transportation sector. It was once believed that integrating solar electricity into distribution systems would be relatively straightforward; however, when the penetration level of photovoltaic (PV) systems began to increase, power utilities faced new and unexpected problems, which arose primarily due to the weak chronological coincidence between PV array production and the system peak demand. PV arrays produce their peak output at noon, during low demand periods, resulting in individual instances when the net PV production exceeds the system net demand. Power then flows from low voltage (LV) to medium voltage (MV) networks. Such reverse power flow results in significant over voltages along distribution feeders and excessive power losses. For PHEVs, the situation is the direct opposite because peak demand periods coincide closely with the hours during which the majority of vehicles are parked at residences and are thus probably being charged. This coincidence causes substantial distribution equipment overloading, hence requiring costly system upgrades. Although extensive research has been conducted with respect to the individual impacts of PV electricity and PHEVs on distribution networks, far too little attention has been paid to studying the interaction between these two technologies or the resulting aggregated impacts when both operate in parallel. The goal of the research presented in this thesis is to fill this gap by developing a comprehensive benchmark that can be used to analyze the performance of the distribution system under a high penetration of both PV systems and PHEVs. However, the uncertainties associated with existing electrical loads, the PHEV charging demand, and the PV array output complicate the achievement of this goal and necessitate the development of accurate probabilistic models to express them. The establishment of such models and their use in the development of the proposed benchmark represent core contributions of the research presented in this thesis. Assessing the anticipated impacts of PHEVs and PV electricity on distribution systems is not the only challenge confronting the electricity sector. Another issue that has been tackled by numerous researchers is the formulation of solutions that will facilitate the integration of both technologies into existing networks. The work conducted for this thesis presents two different solutions that address this challenge: a traditional one involving the use of energy storage systems (ESSs), and an innovative one that hinges on a futuristic novel bilayer (AC-DC) distribution system architecture. In the first solution, the author proposes using ESSs as a possible means of mitigating the aggregated impacts of both PV electricity and PHEVs. This goal can be achieved by storing PV electricity generated during low demand periods, when reverse power flow is most likely to occur, in small-scale dispersed ESSs located at secondary distribution transformers. Thereafter, this energy is then reused to meet part of the PHEV charging demand during peak periods when this demand is most likely to overload distribution equipment. While this solution would kill two birds with one stone, the uncertainties inherent in the system make its implementation difficult. In this respect, a significant contribution of the work presented in this thesis is the use of the previously developed probabilistic benchmark to determine the appropriate sizes, locations, and operating schedules of the proposed ESSs, taking into account the different sources of uncertainty in the system. In the second solution, the author proposes a novel bilayer (AC-DC) architecture for residential distribution systems. With the proposed architecture, the distribution system becomes a bilayer system composed of the traditional AC layer for interfacing with existing system loads, plus an embedded DC layer for interfacing with PV arrays and PHEVs. A centralized bidirectional converter links the two layers and controls the power flow between them. The proposed solution offers a reasonable compromise that enables existing networks to benefit from both AC and DC electricity, thus metaphorically enjoying the best of both worlds. As with the first solution, the uncertainties that characterize the distribution system also create obstacles to the implementation of the proposed architecture. Another important contribution of the research presented in this thesis is the design and validation of the proposed bilayer system, with consideration of these different uncertainties. Finally, the author compares the strengths and weaknesses of both solutions to determine the better alternative

Manetho: Transparent Rollback-Recovery with Low Overhead, Limited Rollback, and Fast Output Commit

Manetho is a new transparent rollback_recovery protocol for long-running distributed computations. It uses a novel combination of antecedence graph maintenance, uncoordinated check pointing, and sender-based message logging. Manetho simultaneously achieves the advantages of pessimistic message logging, namely limited rollback and fast output commit, and the advantage of optimistic message logging, namely low failure-free overhead. These advantages come at the expense of a complex recovery schem

Replicated Processes in Manetho

This paper presents the process­replication protocol of Manetho, a system whose goal is to provide efficient, application­transparent fault tolerance to long­running distributed computations. Manetho uses a new negative­ acknowledgment multicast protocol to enforce the same receipt order of application messages among all replicas of a process. The protocol depends on a combination of antecedence graph maintenance, a form of sender­based message logging, and the fact that the receivers of each multicast execute the same deterministic program. This combination allows our protocol to avoid the delay in application message delivery that is common in exist­ ing negative­acknowledgment multicast protocols, without giving up the advantage of requiring only a small number of control messages

On the Implementation and Use of Message Logging

We present a number of experiments showing that for compute-intensive applications executing in parallel on clusters of workstations, message logging has higher failure-free overhead than coordinated checkpointing. Message logging protocols, however, result in much shorter output latency than coordinated checkpointing. Therefore, message logging should be used for applications involving substantial interactions with the outside world, while coordinated checkpointing should be used otherwise. We also present an unorthodox message logging design that uses coordinated checkpointing with message logging, departing from the conventional approaches that use independent checkpointing. This combination of message logging and coordinated checkpointing offers several advantages, including improved failure-free performance, bounded recovery time, simplified garbage collection, and reduced complexity. Meanwhile, the new protocols retain the advantages of the conventional message logging protocols with respect to output commit. Finally, we discuss three “lessons learned” from an implementation of various message logging protocol

ReverCSP: Time-Travelling in CSP Computations

[EN] This paper presents reverCSP, a tool to animate both forward and backward CSP computations. This ability to reverse computations can be done step by step or backtracking to a given desired state of interest. reverCSP allows us to reverse computations exactly in the same order in which they happened, or also in a causally-consistent way. Therefore, reverCSP is a tool that can be especially useful to comprehend, analyze, and debug computations. reverCSP is an open-source project publicly available for the community. We describe the tool and its functionality, and we provide implementation details so that it can be reimplemented for other languages.This work has been partially supported by the EU (FEDER) and the Spanish MCI/AEI under grants TIN2016-76843-C4-1-R and PID2019- 104735RB-C41, and by the Generalitat Valenciana under grant Prometeo/2019/098 (DeepTrust).Galindo-Jiménez, CS.; Nishida, N.; Silva, J.; Tamarit, S. (2020). ReverCSP: Time-Travelling in CSP Computations. Springer. 239-245. https://doi.org/10.1007/978-3-030-52482-1_14S239245Bernadet, A., Lanese, I.: A modular formalization of reversibility for concurrent models and languages. In: Proceedings of ICE 2016, EPTCS (2016)Brown, G., Sabry, A.: Reversible communicating processes. Electron. Proc. Theor. Comput. Sci. 203, 45–59 (2016)Conserva Filhoa, M., Oliveira, M., Sampaio, A., Cavalcanti, A.: Compositional and local livelock analysis for CSP. Inf. Process. Lett 133, 21–25 (2018)Danos, V., Krivine, J.: Reversible communicating systems. In: Gardner, P., Yoshida, N. (eds.) CONCUR 2004. LNCS, vol. 3170, pp. 292–307. Springer, Heidelberg (2004). https://doi.org/10.1007/978-3-540-28644-8_19Elnozahy, E.N.M., Alvisi, L., Wang, Y.-M., Johnson, D.B.: A survey of rollback- recovery protocols in message-passing systems. ACM Comput. Surv. 34(3), 375–408 (2002)Fang, Y., Zhu, H., Zeyda, F., Fei, Y.: Modeling and analysis of the disruptor framework in csp. In: Proceedings of CCWC 2018. IEEE Computer Society (2018)Ladkin, P.B., Simons, B.B.: Static deadlock analysis for CSP-type communications. In: Fussell, D.S., Malek, M. (eds.) Responsive Computer Systems: Steps Toward Fault-Tolerant Real-Time Systems. The Springer International Series in Engineering and Computer Science, vol. 297, pp. 89–102. Springer, Boston (1995). https://doi.org/10.1007/978-1-4615-2271-3_5Landauer, R.: Irreversibility and heat generation in the computing process. IBM J. Res. Dev. 5, 183–191 (1961)Lanese, I., Antares Mezzina, C., Tiezzi, F.: Causal-consistent reversibility. Bull. EATCS 114, 17 (2014)Lanese, I., Nishida, N., Palacios, A., Vidal, G.: CauDEr: a causal-consistent reversible debugger for erlang. In: Gallagher, J.P., Sulzmann, M. (eds.) FLOPS 2018. LNCS, vol. 10818, pp. 247–263. Springer, Cham (2018). https://doi.org/10.1007/978-3-319-90686-7_16Lanese, I., Palacios, A., Vidal, G.: Causal-consistent replay debugging for message passing programs. In: Pérez, J.A., Yoshida, N. (eds.) FORTE 2019. LNCS, vol. 11535, pp. 167–184. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-21759-4_10Llorens, M., Oliver, J., Silva, J., Tamarit, S.: Dynamic slicing of concurrent specification languages. Parallel Comput. 53, 1–22 (2016)Llorens, M., Oliver, J., Silva, J., Tamarit, S.: Tracking CSP computations. J. Log. Algebr. Meth. Program. 102, 138–175 (2019)Perera, R., Garg, D., Cheney, J.: Causally consistent dynamic slicing. In Proceedings of CONCUR 2016, LIPIcs, vol. 59, pp. 18:1–18:15 (2016)Phillips, I., Ulidowski, I., Yuen, S.: A reversible process calculus and the modelling of the ERK signalling pathway. In: Glück, R., Yokoyama, T. (eds.) RC 2012. LNCS, vol. 7581, pp. 218–232. Springer, Heidelberg (2013). https://doi.org/10.1007/978-3-642-36315-3_18Roscoe, A.W.: The Theory and Practice of Concurrency. Prentice Hall PTR, Upper Saddle River (1997)Zhao, H., Zhu, H., Yucheng, F., Xiao, L.: Modeling and verifying storm using CSP. In: Proceedings of HASE 2019. IEEE Computer Society (2019