Employments on Clément Joly – Open-Source, Rust & SQLitehttps://joly.pw/employment/Recent content in Employments on Clément Joly – Open-Source, Rust & SQLiteClément Joly – Open-Source, Rust & SQLitehttps://joly.pw/images/open-graph-pages.jpghttps://joly.pw/images/open-graph-pages.jpgHugo -- 0.154.3enClément JolyThu, 09 Apr 2026 19:45:12 +0000Software Engineer, Rothesay, Londonhttps://joly.pw/employment/rothesay-2024/Mon, 29 Apr 2024 13:26:11 +0200https://joly.pw/employment/rothesay-2024/StratOS team
  • Responsibilities: improve tooling for quants designing models and migrate systems away from Goldman Sachs proprietary systems
  • Multiple improvements to drive down the CI build time and improve the success rate
  • Wrote scripts to pin down external package versions in Conda environments
  • Improvements to Cloud-based Linux containers used as development environments (Gitpod)
  • Engineering support for end of day risk calculation

    • ✓   Python, Conda, Rust, AWS, SecDB, Gitpod

    ]]>    Software Engineer L4, Paxos, Londonhttps://joly.pw/employment/paxos-2022/Wed, 15 Jun 2022 13:26:11 +0200https://joly.pw/employment/paxos-2022/Brokerage team
  • Responsibilities: design and delivery of a smart order routing system from the ground up, adapting to the quickly evolving requirements of crypto markets
  • Designed the smart order router in a team of three using Go and Rust micro-services
  • Wrote a connector service to internal and external market-places for order execution
  • Drove performance improvements by:
    • Load-testing a production-like system while analyzing metrics and resource usage of the key components
    • Using results to tune SQL indices, RabbitMQ parameters and calls to accounting services developed by other teams
  • Lead cross-team initiatives to spread Rust knowledge and best practices — in particular to catch logical errors at compile time by leveraging the type system
  • Engineering support for customer-facing trading-systems, from REST & FIX APIs to the order-matching engine

    • ✓   Rust, Go, Python, AWS, Postgres, Microservices, Protocol Buffer, RabbitMQ

    • Worked from home (some of the time), took on-call shifts
    • Organized knowledge-sharing sessions to get new team member up to speed or to share insight on the Rust language with colleagues
    ]]>    Software Engineer, Cloudflare, Londonhttps://joly.pw/employment/cloudflare-2020/Mon, 10 Aug 2020 13:26:11 +0200https://joly.pw/employment/cloudflare-2020/Distributed Denial of Service (DDoS) protection team
  • Responsibilities: maintain and improve automated mitigation systems against DoS attacks, answer customer queries
    • Redesigned with a colleague the data pipeline to display network analytics to customers. It involved mainly data extraction using eBPF, efficient and performant storage in ClickHouse and a public facing GraphQL API
    • Extended and automated data extraction for public reports like “Network-layer DDoS attack trends for Q4 2020”
    • Optimized directly-written eBPF assembly, C code, ClickHouse tables and materialized views
    • Troubleshooted, fixed bugs and extended the Gatebot Python codebase
    • Co-authored the blog post “How we built Network Analytics v2”

    ✓   C, eBPF, XDP, Rust, Go, Python, Docker, TCP, UDP, dos attacks, ClickHouse, GraphQL

    • Worked from home (part of the time), took oncall shifts
    • Organized knowledge-sharing sessions to get new team member up to speed or to share insight from a research paper with colleagues
    ]]>    Software Developer Intern, Cloudflare, Londonhttps://joly.pw/employment/cloudflare-internship-2020/Tue, 10 Mar 2020 13:26:11 +0200https://joly.pw/employment/cloudflare-internship-2020/Distributed Denial of Service (DDoS) team
  • Aim: benchmark, develop and compare various performance optimizations in l4drop, a DoS mitigation system
  • Presented the methodology and results at the Linux Plumbers Conference and in my master thesis

    • ✓   eBPF, XDP, TCP, kernel probes, Python

    • Worked from home almost from the beginning
    • Worked in English on a daily basis.
    ]]>    Software Developer Intern, SnT, Luxembourghttps://joly.pw/employment/snt-2019/Sat, 15 Jun 2019 13:26:11 +0200https://joly.pw/employment/snt-2019/Interdisciplinary Center for Security, Reliability and Trust (SnT), a research lab of the University of Luxembourg. [securityandtrust.lu](http://securityandtrust.lu)
  • Aim: explore performance analysis technics with eBPF (extended Berkeley Packet Filter)
  • Wrote IP-whitelisting tool using XDP for DDoS protection of a Ripple blockchain connector
  • Extended Vector monitoring tool with additional eBPF modules : packet analysis (HTTP & WebSocket, UDP & DTLS), garbage collector visualization for NodeJS using USDT probes
  • Co-authored a research paper outlining innovative performance monitoring schemes
  • Worked in English on a daily basis.

    • ✓   eBPF at different levels, Docker, Python, Go, TCP, UDP, Websocket

    ]]>    Freelance work for a junior company (Télécom Nancy Services)https://joly.pw/employment/tns2019/Tue, 15 Jan 2019 13:26:11 +0200https://joly.pw/employment/tns2019/Android app sold to a bakery
  • Stored recurring and one-time orders; planed and recorded product delivery to bill each customer
  • Saved hours each month: planning and billing delivery was done manually on paper before

    • ✓   Android, Java, SQL, SQLite, Room ORM

    • An easy to use interface was mandatory
    • Learned Android development by myself, on phone and tablet
    Customer list

    Adding a new order for a customer
    Completed order for a customer
    View of a customer with its next deliveries
    Adding a recurring order
    Editing the informations of a customer
    Adding a customer’s vacations

    A customer before delivery
    A customer after delivery

    View of products sold
    Export screen
    Overview of the orders of a customer

    ]]>    Worker at a pharmacy (1 month)https://joly.pw/employment/pharmacy-2018/Mon, 10 Sep 2018 13:26:11 +0200https://joly.pw/employment/pharmacy-2018/delivered meds to customers, stored products by type/name