Introduction

ISUCON Official Blog

ISUCON is a contest where teams compete to optimize a given web service for maximum performance. The key is to identify and resolve bottlenecks through repeated cycles of tuning and measurement.

Key Concepts

• Resolve service bottlenecks:
  • Repeat "tune → measure → find bottleneck"
• Resolve team bottlenecks:
  • Divide tasks so no one is blocked
  • Avoid interfering with each other's work
• Resolve development bottlenecks:
  • Make small commits with clear messages
  • Use an environment that allows quick rollbacks (e.g., GitHub pull requests and revert)
  • ISUCON scoring is strict—always ensure you can revert failed changes

Tips

• Don't start coding blindly. Spend the first 30 minutes reading documentation and confirming service behavior.
• Understand user stories, benchmark behavior, and scoring.
• Identify critical and non-critical endpoints.
• Benchmark scores are not always the best indicator—focus on bottleneck analysis.
• Use logs and metrics to analyze where the bottlenecks are (e.g., Nginx access log, MySQL slow query log, Netdata, pprof).

Team Structure

A typical team structure is App - App - DB/Infra.

• App:
  • Fix N+1 queries
  • Implement memory caching
  • Parallelize external API calls
  • Avoid deadlocks
• DB:
  • Adjust indexes
  • Change schema as needed
  • Optimize queries
• Infra:
  • Manage deployment and benchmarking
  • Install and tune middleware
  • Analyze logs
  • Handle multi-server distribution