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Code Execution — Notes#

Functional#

  • Compile + run user code in many languages.
  • Run against test cases; score.
  • Stream output back.

Non-functional#

  • p99 < 3 s typical contest run.
  • Isolation against fork bombs, network probes, side channels.
  • 99.95% uptime.

Capacity#

  • Contest spikes: tens of thousands of submissions/min.
  • Worker fleet autoscaled to queue depth.

Trade-offs#

  • Containers = fast cold start; microVMs = stronger isolation.
  • Warm pool of pre-launched runtimes saves startup latency.
  • Hidden tests must remain server-side; never ship to client.

Refs#

  • Firecracker (AWS) paper.
  • HackerRank / LeetCode / Codeforces engineering posts.
  • gVisor / Kata Containers docs.
  • Replit / CodeSandbox architecture posts.