ReusePort Demo

This project demonstrates how to build and test a Rust web server that uses SO_REUSEPORT to allow multiple instances of the same process to listen on the same TCP port and share incoming connections.

What We Did

• Implemented a simple Axum-based HTTP server in Rust.
• Configured the listener socket with SO_REUSEPORT so that multiple server processes can bind to the same port.
• Each instance responds on /pid endpoint with its process ID, so we can see which instance handled each request.

How We Tested

• Wrote a shell test script tests/test_reuseport.sh that:
  1. Builds the Rust server (cargo build).
  2. Starts multiple instances of the server on the same port (using SO_REUSEPORT).
  3. Sends many HTTP requests to /pid using curl.
  4. Collects the returned PIDs and summarizes the distribution.
• Added Python script tests/test_uniform.py that:
  • Reads request/response logs from stdin.
  • Performs a Chi-square goodness-of-fit test to check if the distribution of requests across PIDs is uniform.
  • Outputs Chi-square, p-value, and a human-readable “randomness rating” with color icons.

Example Output

SUMMARY  22573  17
SUMMARY  22574  16
SUMMARY  22575  15
SUMMARY  22576  16
Total    64
Chi-square: 0.250
p-value:   0.969
RANDOMNESS: 🟢 Excellent
SCALE: 🟢 ≥ 0.20 (Excellent), 🟡 ≥ 0.05 (Good), 🟠 ≥ 0.01 (Fair), 🔴 < 0.01 (Poor)

Requirements

• Rust toolchain
• Bash
• lsof
• Python 3 with SciPy and NumPy

Run Tests

chmod +x tests/*.{sh,py}
./tests/test_reuseport.sh | python3 tests/test_uniform.py

This will build the server, run multiple instances, send requests, and analyze whether the load balancing across processes is uniform.