Find fastest download server / mirror.

find-fastest-mirror.sh

#!/usr/bin/env bash
# Find the fastest mirror from a list of servers
# Tests HTTP(S) response time using curl's time_connect + time_starttransfer

TIMEOUT=5
PARALLEL=8   # max concurrent jobs

SERVERS=(
  adectra.com
  akane.network
  arizona.edu
  arlm.tyzoid.com
  bloomu.edu
  brightlight.today
  cdn-perfprod.com
  cicku.me
  clarkson.edu
  colonelhosting.com
  constant.com
  cs.odu.edu
  customcomputercare.com
  ette.biz
  fcix.net
  geo.mirror.pkgbuild.com
  givebytes.net
  goober.cloud
  hasphetica.win
  hu.fo
  hugeblank.dev
  ialab.dsu.edu
  iu13.org
  k0.ae
  kernel.org
  lahansons.com
  leaseweb.net
  logal.dev
  lug.mtu.edu
  m.lqy.me
  marcusspencer.us
  miningtcup.me
  mirrors.shr.cx
  misaka.one
  mit.edu
  mra.sh
  niranjan.co
  ocf.berkeley.edu
  octyl.net
  osuosl.org
  pilotfiber.com
  rackspace.com
  rcac.purdue.edu
  rit.edu
  smeal.xyz
  soulharsh007.dev
  teraswitch.com
  theash.xyz
  umd.edu
  vectair.net
  xtom.com
  yonderly.org
  zackmyers.io
  zxcvfdsa.com
)

TMPDIR_RESULTS=$(mktemp -d)
trap 'rm -rf "$TMPDIR_RESULTS"' EXIT

measure() {
  local host="$1"
  local result

  result=$(curl -sSo /dev/null \
    --max-time "$TIMEOUT" \
    --connect-timeout "$TIMEOUT" \
    -w "%{time_connect} %{time_starttransfer}" \
    -L --max-redirs 3 \
    "https://${host}/" 2>/dev/null)

  if [[ -z "$result" ]]; then
    printf "%-40s  UNREACHABLE\n" "$host" > "$TMPDIR_RESULTS/$host"
    return
  fi

  local t_connect t_ttfb total
  t_connect=$(echo "$result" | awk '{print $1}')
  t_ttfb=$(echo "$result" | awk '{print $2}')

  # Use TTFB (time to first byte) as the ranking metric; 0.000 means failed
  if [[ "$t_ttfb" == "0.000000" || "$t_ttfb" == "0" ]]; then
    printf "%-40s  UNREACHABLE\n" "$host" > "$TMPDIR_RESULTS/$host"
  else
    total=$(awk "BEGIN {printf \"%.4f\", $t_ttfb}")
    printf "%-40s  %s s  (connect: %s s)\n" "$host" "$total" "$t_connect" \
      > "$TMPDIR_RESULTS/$host"
  fi
}

export -f measure
export TIMEOUT TMPDIR_RESULTS

echo "Testing ${#SERVERS[@]} mirrors (timeout: ${TIMEOUT}s, parallel: ${PARALLEL})..."
echo "---"

# Run measurements in parallel using a job pool
active=0
for host in "${SERVERS[@]}"; do
  measure "$host" &
  (( active++ ))
  if (( active >= PARALLEL )); then
    wait -n 2>/dev/null || wait   # wait for any one job (-n requires bash 4.3+)
    (( active-- ))
  fi
done
wait

echo ""
echo "=== Results (sorted by TTFB) ==="
echo ""

# Separate reachable from unreachable, sort reachable by TTFB
REACHABLE=()
UNREACHABLE=()

for host in "${SERVERS[@]}"; do
  line=$(cat "$TMPDIR_RESULTS/$host" 2>/dev/null)
  if [[ "$line" == *"UNREACHABLE"* ]]; then
    UNREACHABLE+=("$line")
  else
    REACHABLE+=("$line")
  fi
done

# Sort reachable results by the TTFB column (field 2)
printf '%s\n' "${REACHABLE[@]}" | sort -k2 -n

if (( ${#UNREACHABLE[@]} > 0 )); then
  echo ""
  echo "--- Unreachable ---"
  printf '%s\n' "${UNREACHABLE[@]}"
fi

echo ""
echo "=== FASTEST MIRROR ==="
BEST=$(printf '%s\n' "${REACHABLE[@]}" | sort -k2 -n | head -1)
echo "$BEST"