Career History

Note: 2024 information is currently being updated

**Ginco Inc. [2017/12 - Present]**

• Platform Department (formerly SRE Department) Director / Senior Engineer [-Present]
  • Main responsibilities:
    • Annual roadmap formulation/execution
    • Recruitment / Training
    • Globalization
  • Introduced bare metal to blockchain node infrastructure [2024]
    • Reduced infrastructure costs by 40%, saving 84 million yen annually
    • Reduced API cost per RPC by 1/2 to 1/4
  • Department globalization [2023-2024]
    • Hired 6 overseas engineers (India)
  • Revamped blockchain node infrastructure and migrated to Google Cloud [2023]Google Cloud Day '23 Tour
  • Established SRE Department [2021]
    • Formulated team mission and OKRs, built a self-directed team
    • Implemented SLOs and built SLO dashboard, achieving continuous improvement in collaboration with management
  • SLO improvement [2020]
    • Built monitoring infrastructure
    • Improved API response latency by 5x
  • Cost reduction [2020]
    • Reduced infrastructure costs by 55% without performance degradation
• Tech Lead [-2019/12]
  • Launched enterprise crypto asset wallet system
    • Responsible for requirements definition, backend and infrastructure design and development
    • Newly adopted gRPC and microservices architecture
      • Balanced development scale and speed
      • Service division allowed non-backend engineers to participate in development
• Backend Engineer [-2018/12]
  • Responsible for design and development of cryptocurrency wallet app

**MC DIGITAL Inc. [2021/03-2024/04] (Contract)**

• Architect
  • Design and development of large-scale data infrastructure (data lake, ETL, data warehouse)
  • Design and development of ML systems (infrastructure)
• SRE
  • Improved incident response
  • ML systems (AI Platform, Airflow, Dataflow)
    • Performance improvement
    • Test implementation
    • CI/CD
    • Definition and monitoring of reliability
• Management support

**Recruit Holdings Co., Ltd. [2017/04 - 2018/03]**

• Implemented framework, developed authentication, and established development guidelines for new Air series products
• Responsible for backend development of Air Weight

Presentations and Articles

• Improving Development Efficiency and Cost Reduction: Revamping Blockchain Node Infrastructure Using GKEGoogle Cloud Day '23 Tour
• Accelerating Cold Start of Cloud FunctionsHow we reduced cold start time of Cloud Functions at Ginco Inc.Cloud Functions Usage and Optimization at Ginco
• Impact of Context Switching on Productivity and Countermeasures, Improvement ExamplesImpact of Context Switching on Productivity and Countermeasures, Improvement Examples
• "A Study on the Number of Graftable Bugs in Automated Program Repair," Computer Software, volume 33, number 3, pages 81-87, August 2016.Soichi Sumi, Yoshiki Higo, Keisuke Hotta, Shinji Kusumoto,
• "Toward Improving Graftability on Automated Program Repair," 31st International Conference on Software Maintenance and Evolution, pages 511-515, October 2015.Soichi Sumi, Yoshiki Higo, Keisuke Hotta, and Shinji Kusumoto
• "A Method for Speeding Up Automated Program Repair by Predicting Next Changes," Master thesis, Graduate School of Information Science and Technology, Osaka University, 2017Soichi Sumi