une version en haskell

{-# LANGUAGE OverloadedStrings #-}
import Control.Concurrent.STM
import qualified Data.ByteString.Char8 as C
import Fmt
import Network.Wai 
import Network.HTTP.Types
import Network.Wai.Handler.Warp 
import System.Environment
import System.Random.Stateful
import Text.Read 
app :: RandomGen g => Int -> TGenM g -> Application
app nImgs rngVar _ respond = do
 i <- atomically $ applyTGen (uniformR (1, nImgs)) rngVar
 let url = fmt $ "https://avatar.spacefox.fr/Renard-" +| i |+ ".png"
 respond $ responseLBS status302 [("Location", url)] ""
main :: IO ()
main = do
 args <- fmap readMaybe <$> getArgs
 rngVar <- getStdGen >>= newTGenMIO
 case args of
 [Just port, Just nImgs] -> do
 C.putStrLn $ fmt $ "listening on port " +| port |+ ""
 run port (app nImgs rngVar)
 _ -> C.putStrLn "usage: <port> <nImgs>"

compilation/exécution:

$ ghc -O2 -rtsopts serve.hs
$ ./serve 8080 21

benchmark (AMD Ryzen 7 PRO 4750U, 1.7GHz) :

$ ab -n 100000 -c 10 http://localhost:8080/
This is ApacheBench, Version 2.3 <$Revision: 1879490 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking localhost (be patient)
Completed 10000 requests
Completed 20000 requests
Completed 30000 requests
Completed 40000 requests
Completed 50000 requests
Completed 60000 requests
Completed 70000 requests
Completed 80000 requests
Completed 90000 requests
Completed 100000 requests
Finished 100000 requests
Server Software: Warp/3.3.20
Server Hostname: localhost
Server Port: 8080
Document Path: /
Document Length: 0 bytes
Concurrency Level: 10
Time taken for tests: 5.373 seconds
Complete requests: 100000
Failed requests: 0
Non-2xx responses: 100000
Total transferred: 13157347 bytes
HTML transferred: 0 bytes
Requests per second: 18612.30 [#/sec] (mean)
Time per request: 0.537 [ms] (mean)
Time per request: 0.054 [ms] (mean, across all concurrent requests)
Transfer rate: 2391.49 [Kbytes/sec] received
Connection Times (ms)
 min mean[+/-sd] median max
Connect: 0 0 0.0 0 1
Processing: 0 0 0.1 0 6
Waiting: 0 0 0.1 0 5
Total: 0 1 0.1 1 6
Percentage of the requests served within a certain time (ms)
 50% 1
 66% 1
 75% 1
 80% 1
 90% 1
 95% 1
 98% 1
 99% 1
 100% 6 (longest request)