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Backend Engineer（Message Queue Platform）｜LY Corporation

Salary: 700 - 1800 百万円

ScalaKafkaPrometheusGrafanaJava
LINEヤフー

Backend Engineer (Message Queue Platform)

Position Outline

The platform team operates one of the world's largest Kafka-based data infrastructures, processing over 1 trillion messages per day in real-time to support messaging, news, advertising, and other services with the highest standards of reliability and performance. Join us to help evolve this critical infrastructure for growing scale and future challenges. The team actively contributes to the OSS community and shares technical insights externally.

Example Technical Talks

  • One Day, One Data Hub - 100 Billion Messages with Kafka (Kafka Summit SF 2017)
  • Investigating Request Delay in a Large-Scale Kafka Cluster Caused by TCP (LINE DEVELOPER DAY 2021)
  • [KAFKA-4614] Long GC pause harming broker performance which is caused by mmap objects
  • KIP-764: Configurable backlog size for creating Acceptor

Responsibilities

  • Design, develop, and enhance the Message Queue platform (including advanced monitoring, automation, capacity planning, etc.)
  • Improve and extend Apache Kafka functionality, including contributions to the OSS community
  • Architect and implement solutions with strong data governance and security requirements
  • Provide technical support and troubleshooting for internal development teams
  • Develop and maintain distributed processing libraries and related tools

Note: Duties may be reassigned based on organizational needs.

Ideal Candidate

  • Thrives on large-scale challenges: Excited by enormous traffic volumes
  • Self-driven and improvement-minded: Can independently plan, identify, and resolve issues; enjoys rapid, incremental improvements
  • Team collaborator and user-focused: Communicates openly; considers internal user viewpoints, finding improvement ideas from various usage patterns
  • Methodical problem-solver: Investigates root causes, verifies carefully, and explains issues clearly

Required Skills & Experience

  • Proficiency in at least one backend language (e.g., Java, Scala)
  • System design and operational experience in Unix-based OS environments

Preferred Skills & Experience

  • Operation and development experience with distributed messaging platforms (Apache Kafka, Apache Pulsar, etc.)
  • Knowledge of distributed consensus algorithms (e.g., Raft, Paxos)
  • Understanding of Linux kernel, network protocols, storage systems, and experience solving performance issues
  • Familiarity with monitoring tools (Prometheus, Grafana, etc.)
  • OSS contribution experience
  • Record of optimizing large-scale distributed systems
  • Master’s or Doctoral degree in Computer Science or a related field

Development Environment

  • Languages: Java, Scala, Python, Rust, Go
  • Observability: Prometheus, Grafana, AlertManager, Elasticsearch, ClickHouse, Redash
  • Infrastructure: Kubernetes, VMs/Physical Machines on Private Cloud
  • IaC & CI/CD: Ansible, ArgoCD, Jenkins, GitHub Actions

Salary

  • Expected Annual Salary: JPY 7,000,000 – 18,000,000
  • Monthly Salary: JPY 467,000 – 1,200,000
    • Base Salary: JPY 361,000 – 934,000
    • Fixed Overtime Allowance (35h): JPY 105,000 – 267,000
  • Overtime above 35h/month is paid separately
  • Bonuses: Up to 2x per year, based on company & department performance

Allowances

  • Overtime allowance
  • Commuting allowance (up to JPY 150,000/month for office days)
  • Remote work improvement allowance (JPY 11,000/month)

Employment Type

  • Permanent employee (no fixed term, 3-month probationary period)

Work Location

  • Tokyo (Kioicho Office)
    • Onsite requirement: 1 day per week minimum
    • Offices are wheelchair accessible
    • Non-smoking indoors (smoking rooms available)

Work Hours

  • Flextime system, standard 7h 45m per day, no core time
    • Company's standard hours: 9:30 a.m. to 6:15 p.m.
  • Shortened hours available for childcare/caregiving
  • Department schedules may vary

Holidays & Leave

  • Days Off: Two-day weekends (Sat/Sun), national holidays, New Year (Dec 29–Jan 4)
    • May vary by department
  • Leave: Paid leave, special paid leave (condolence, maternity, childcare, etc.), Happy Friday, sabbatical

Benefits

  • Full social insurance (health, nursing, pension, employment, worker’s compensation)
  • Defined Contribution Pension Plan
  • Group insurance programs (welfare, disability)
  • Employee savings and investment programs
  • Subsidies for health exams, in-house massage, club/social events

Talent Development & Support

  • Employee training, language courses, management training
  • Internal job challenge system, sabbatical, doctoral study support program

Selection Process

  1. Application
  2. Coding Test / Assignment
  3. Interviews & Background Check
  4. Offer

Note: Document screening, technical assessments, and reference checks are conducted as part of the process. The complete process typically takes 4–6 weeks.

Learn More

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