How to Build an HTTP Server Request Duration Histogram in Python

import time
import random
from collections import Counter
from http.server import HTTPServer, BaseHTTPRequestHandler


class HistogramHandler(BaseHTTPRequestHandler):
    response_times = Counter()

    def do_GET(self):
        start = time.perf_counter()
        time.sleep(random.uniform(0.001, 0.1))
        duration_ms = (time.perf_counter() - start) * 1000
        bucket = round(duration_ms / 10) * 10
        self.response_times[bucket] += 1
        self.send_response(200)
        self.end_headers()
        self.wfile.write(f"duration={duration_ms:.2f}ms bucket={bucket}ms\n".encode())

    def log_message(self, format, *args):
        pass


if __name__ == "__main__":
    server = HTTPServer(("localhost", 8000), HistogramHandler)
    print("Serving on http://localhost:8000 — press Ctrl+C to stop")
    try:
        server.serve_forever()
    except KeyboardInterrupt:
        print("\nResponse time histogram (ms):")
        for bucket in sorted(HistogramHandler.response_times):
            count = HistogramHandler.response_times[bucket]
            print(f"{bucket:>4}ms: {'#' * count} ({count})")
        server.shutdown()