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[PDS/HPDA Seminar] 28/1/2022 from 10:00 to 11:00 at 4A312 - Mouhamadou Tidiane Mamgassouba (reading group) and Paul Frambot (reading group)

During the PDS/HPDA Seminar of 28/1/2022 from 10:00 to 11:00, Mouhamadou Tidiane Mamgassouba will present a reading group talk and Paul Frambot will present a reading group talk.

Visio : https://webconf.imt.fr/frontend/fra-vcg-byn-fxd

Location : 4A312

# Reading group : From Laptop to Lambda : Outsourcing Everyday Jobs to Thousands of Transient Functional Containers (USENIX ATC’19)\n\nPresented by Mouhamadou Tidiane Mamgassouba on 28/1/2022 at 10:00. Attending this presentation is mandatory for the master students.

Paper : https://www.usenix.org/system/files/atc19-fouladi.pdf

Full post : https://www.inf.telecom-sudparis.eu/pds/seminars_cpt/from-laptop-to-lambda-outsourcing-everyday-jobs-to-thousands-of-transient-functional-containers/

## Abstract
We present gg, a framework and a set of command-line tools that helps people execute everyday applications—e.g., software compilation, unit tests, video encoding, or object recognition—using thousands of parallel threads on a cloudfunctions service to achieve near-interactive completion times. In the future, instead of running these tasks on a laptop, or keeping a warm cluster running in the cloud, users might push a button that spawns 10,000 parallel cloud functions to execute a large job in a few seconds from start. gg is designed to make this practical and easy. With gg, applications express a job as a composition of lightweight OS containers that are individually transient (lifetimes of 1–60 seconds) and functional (each container is hermetically sealed and deterministic). gg takes care of instantiating these containers on cloud functions, loading dependencies, minimizing data movement, moving data between containers, and dealing with failure and stragglers. We ported several latency-sensitive applications to run on gg and evaluated its performance. In the best case, a distributed compiler built on gg outperformed a conventional tool (icecc) by 2–5×, without requiring a warm cluster running continuously. In the worst case, gg was within 20% of the hand-tuned performance of an existing tool for video encoding (ExCamera).

# Reading group : Agent-Based Simulations of Blockchain protocols illustrated via Kadena’s Chainweb (EuroS&P Workshops)\n\nPresented by Paul Frambot on 28/1/2022 at 10:30. Attending this presentation is mandatory for the master students.

Paper : https://arxiv.org/pdf/1904.12924.pdf

Full post : https://www.inf.telecom-sudparis.eu/pds/seminars_cpt/agent-based/

## Abstract
While many distributed consensus protocols provide robust liveness and consistency guarantees under the presence of malicious actors, quantitative estimates of how economic incentives affect security are few and far between. In this paper, we describe a system for simulating how adversarial agents, both economically rational and Byzantine, interact with a blockchain protocol. This system provides statistical estimates for the economic difficulty of an attack and how the presence of certain actors influences protocol-level statistics, such as the expected time to regain liveness. This simulation system is influenced by the design of algorithmic trading and reinforcement learning systems that use explicit modeling of an agent’s reward mechanism to evaluate and optimize a fully autonomous agent. We implement and apply this simulation framework to Kadena’s Chainweb, a parallelized Proof-of-Work system, that contains complexity in how miner incentive compliance affects security and censorship resistance. We provide the first formal description of Chainweb that is in the literature and use this formal description to motivate our simulation design. Our simulation results include a phase transition in block height growth rate as a function of shard connectivity and empirical evidence that censorship in Chainweb is too costly for rational miners to engage in. We conclude with an outlook on how simulation can guide and optimize protocol development in a variety of contexts, including Proof-of-Stake parameter optimization and peer-to-peer networking design.