Responding to requests concurrently in the Racket Web server

ab.log

This is ApacheBench, Version 2.3 <$Revision: 1604373 $>
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).....done


Server Software:        Racket
Server Hostname:        localhost
Server Port:            9000

Document Path:          /test
Document Length:        50 bytes

Concurrency Level:      5
Time taken for tests:   20.094 seconds
Complete requests:      50
Failed requests:        0
Total transferred:      11750 bytes
HTML transferred:       2500 bytes
Requests per second:    2.49 [#/sec] (mean)
Time per request:       2009.350 [ms] (mean)
Time per request:       401.870 [ms] (mean, across all concurrent requests)
Transfer rate:          0.57 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       0
Processing:  2004 2009   2.7   2009    2017
Waiting:     2004 2009   2.7   2008    2017
Total:       2005 2009   2.8   2009    2017

Percentage of the requests served within a certain time (ms)
  50%   2009
  66%   2009
  75%   2010
  80%   2010
  90%   2015
  95%   2016
  98%   2017
  99%   2017
 100%   2017 (longest request)

t.log

Your Web application is running at http://localhost:9000.
Stop this program at any time to terminate the Web Server.
REQUEST @ 1430218137
REQUEST @ 1430218137
REQUEST @ 1430218137
REQUEST @ 1430218137
REQUEST @ 1430218137
RESPONSE @ 1430218139 :: #f
RESPONSE @ 1430218139 :: #f
RESPONSE @ 1430218139 :: #f
RESPONSE @ 1430218139 :: #f
RESPONSE @ 1430218139 :: #f
REQUEST @ 1430218139
REQUEST @ 1430218139
REQUEST @ 1430218139
REQUEST @ 1430218139
REQUEST @ 1430218139
RESPONSE @ 1430218141 :: #f
RESPONSE @ 1430218141 :: #f
RESPONSE @ 1430218141 :: #f
RESPONSE @ 1430218141 :: #f
RESPONSE @ 1430218141 :: #f
REQUEST @ 1430218141
REQUEST @ 1430218141
REQUEST @ 1430218141
REQUEST @ 1430218141
REQUEST @ 1430218141
RESPONSE @ 1430218143 :: #f
RESPONSE @ 1430218143 :: #f
RESPONSE @ 1430218143 :: #f
RESPONSE @ 1430218143 :: #f
RESPONSE @ 1430218143 :: #f
REQUEST @ 1430218143
REQUEST @ 1430218143
REQUEST @ 1430218143
REQUEST @ 1430218143
REQUEST @ 1430218143
RESPONSE @ 1430218145 :: #f
RESPONSE @ 1430218145 :: #f
RESPONSE @ 1430218145 :: #f
RESPONSE @ 1430218145 :: #f
RESPONSE @ 1430218145 :: #f
REQUEST @ 1430218145
REQUEST @ 1430218145
REQUEST @ 1430218145
REQUEST @ 1430218145
REQUEST @ 1430218145
RESPONSE @ 1430218147 :: #f
RESPONSE @ 1430218147 :: #f
RESPONSE @ 1430218147 :: #f
RESPONSE @ 1430218147 :: #f
RESPONSE @ 1430218147 :: #f
REQUEST @ 1430218147
REQUEST @ 1430218147
REQUEST @ 1430218147
REQUEST @ 1430218147
REQUEST @ 1430218147
RESPONSE @ 1430218149 :: #f
RESPONSE @ 1430218149 :: #f
RESPONSE @ 1430218149 :: #f
RESPONSE @ 1430218149 :: #f
RESPONSE @ 1430218149 :: #f
REQUEST @ 1430218149
REQUEST @ 1430218149
REQUEST @ 1430218149
REQUEST @ 1430218149
REQUEST @ 1430218149
RESPONSE @ 1430218151 :: #f
RESPONSE @ 1430218151 :: #f
RESPONSE @ 1430218151 :: #f
RESPONSE @ 1430218151 :: #f
RESPONSE @ 1430218151 :: #f
REQUEST @ 1430218151
REQUEST @ 1430218151
REQUEST @ 1430218151
REQUEST @ 1430218151
REQUEST @ 1430218151
RESPONSE @ 1430218153 :: #f
RESPONSE @ 1430218153 :: #f
RESPONSE @ 1430218153 :: #f
RESPONSE @ 1430218153 :: #f
RESPONSE @ 1430218153 :: #f
REQUEST @ 1430218153
REQUEST @ 1430218153
REQUEST @ 1430218153
REQUEST @ 1430218153
REQUEST @ 1430218153
RESPONSE @ 1430218155 :: #f
RESPONSE @ 1430218155 :: #f
RESPONSE @ 1430218155 :: #f
RESPONSE @ 1430218155 :: #f
RESPONSE @ 1430218155 :: #f
REQUEST @ 1430218155
REQUEST @ 1430218155
REQUEST @ 1430218155
REQUEST @ 1430218155
REQUEST @ 1430218155
RESPONSE @ 1430218157 :: #f
RESPONSE @ 1430218157 :: #f
RESPONSE @ 1430218157 :: #f
RESPONSE @ 1430218157 :: #f
RESPONSE @ 1430218157 :: #f

t.rkt

#lang racket/base
(require web-server/http
         web-server/servlet-env)

(define (start req)
  (define request-start/s (current-seconds))
  (printf "REQUEST @ ~a\n" request-start/s)
  ;; long I/O, fetch from a web service or some such
  (thread-wait (thread (λ () (sleep 2))))
  (define request-end/s (current-seconds))
  (begin0
    (response/full
     200
     #"Okay"
     request-end/s
     #"text/plain"
     null
     (list (string->bytes/utf-8
            (format "request/response interval ~a -> ~a"
             request-start/s request-end/s))))
    (printf "RESPONSE @ ~a :: ~a\n" request-end/s #f)
    (flush-output)))

(serve/servlet start
               #:port 9000
               #:command-line? #t
               #:banner? #t
               #:listen-ip #f
               #:servlet-regexp #rx"")

t.sh

% racket -t t.rkt 2>&1 | tee t.log
% ab -n 50 -c 5 http://localhost:9000/test 2>&1 | tee ab.log