Tests HTTP mirrors of Cygwin by measuring download times.

cygwin-mirror-speed.py

#!/usr/bin/env python3
"""
Script to test HTTP mirrors of Cygwin by measuring download times.

Originally written in 2011, modernized in 2025.
"""
from math import floor
from urllib.request import urlopen
import argparse
import sys
import random
import time
import ssl
import certifi
import concurrent.futures
import multiprocessing


__author__ = 'Dmitry Sidorenko'
__maintainer__ = 'Dmitry Sidorenko (@ushkinaz on GitHub)'
__last_updated__ = '2025-02-22'

MIRRORS_URL = "https://cygwin.com/mirrors.lst"
TEST_FILE = "/x86_64/setup.ini"
BLOCK_SZ = 8096

default_threads: int  = floor(multiprocessing.cpu_count()/2)

parser = argparse.ArgumentParser(description="Test Cygwin HTTP(S) mirrors for speed.")
parser.add_argument("--limit", type=int, default=9999,
                    help="Limit the number of mirrors to test (default: all available)")
parser.add_argument("--timeout", type=int, default=5,
                    help="Timeout for each request in seconds (default: 5)")
parser.add_argument("--top", type=int, default=5,
                    help="Number of fastest mirrors to show (default: 5)")
parser.add_argument("--parallel", type=int, default=default_threads,
                    help=f"Number of threads to use. Values higher than number of CPU cores may negatively affect download times. (default: {default_threads})")
parser.add_argument("--include-noshow", action="store_true",
                    help="Include redundant legacy mirrors marked as 'noshow' (default: False)")
parser.add_argument("-s", "--silent", action="store_true",
                    help="Suppress output (only show results)")

args = parser.parse_args()

max_hosts_to_try: int = args.limit
request_timeout: int = args.timeout
max_top_mirrors: int = args.top
include_noshow: bool = args.include_noshow
parallel: int = args.parallel
verbose_mode: bool = not args.silent

mirrors = [
    #    {"host": [],
    #     "time": 1.0
    #  }
]

def test_mirror(host_entry):
    """Test a single mirror and measure its response time."""
    host = host_entry["host"]
    url = f"{host[0]}{TEST_FILE}"

    start_time = time.time()
    try:
        with urlopen(url, timeout=request_timeout) as response:
            response.read(BLOCK_SZ)  # Read a small block to trigger connection
        elapsed_time = time.time() - start_time
    except Exception:
        elapsed_time = float("inf")  # If failure, set to infinity

    host_entry["time"] = elapsed_time
    if verbose_mode:
        elapsed_str = "timeout" if elapsed_time == float("inf") else f"{elapsed_time:.2f}s"
        print(f"{host[1]:>{max_host_len}} - {elapsed_str}")

    return host_entry  # Return result


if verbose_mode:
    print("Retrieving mirror list...", end='')
    sys.stdout.flush()

max_host_len = 0
context = ssl.create_default_context(cafile=certifi.where())
response = urlopen(MIRRORS_URL, context=context).read().decode("utf-8")
for line in response.splitlines():
    host = line.split(";")
    # Only test http(s)
    if host[0].startswith("http") and (include_noshow or len(host) < 5 or host[4] != "noshow"):
        mirrors.append({"host": host, "time": 9999.0})
if verbose_mode:
    print(f"done, {len(mirrors)} entries.")

if max_hosts_to_try == 9999:
    max_hosts_to_try = len(mirrors)

if verbose_mode:
    print(f"Checking {max_hosts_to_try} mirrors...\n")

mirrors_to_test = random.sample(mirrors, min(max_hosts_to_try, len(mirrors)))
max_host_len = max(len(host["host"][1]) for host in mirrors_to_test) + 1

with concurrent.futures.ThreadPoolExecutor(max_workers=parallel) as executor:
    mirrors = list(executor.map(test_mirror, mirrors_to_test))

mirrors = sorted(mirrors, key=lambda entry: entry["time"])

actual_top_mirrors = min(max_hosts_to_try, max_top_mirrors)

if verbose_mode:
    print(f"\nTop {actual_top_mirrors} fastest mirrors:\n", file=sys.stderr)

for i in range(actual_top_mirrors):
    mirror = mirrors[i]
    host_info = mirror["host"]
    if mirror["time"] < 9999:
        print("%.3f, %14s, %15s, %s" % (mirror["time"], host_info[2], host_info[3], host_info[0]), file=sys.stderr)

works like a charm, thanks

Very nice tool, thanks!

Nice, thanks for this!

works great thank you!

That is amazing! thank you so much!

Very nice, thanks!

awesome!

Cool script. Saved my time.

That's so great, thanks : )

if you got an error ..timeout replace test_file = "/setup.ini" to test_file = "x86/setup.ini"

Thanks !

...So is this testing ping or speed?

...So is this testing ping or speed?

It's testing speed by downloading single file from each mirror

Works Great! Thank you!