Example for demonstration request count limit with big event loop deleay

Output

➜ ~ ab -c 20 -n 1000 http://localhost:3000/                                                                                                      ([email protected]:formelife-develop)(gke_formelife-develop_us-central1_cluster-develop/default)
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 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Completed 600 requests
Completed 700 requests
Completed 800 requests
Completed 900 requests
Completed 1000 requests
Finished 1000 requests


Server Software:
Server Hostname:        localhost
Server Port:            3000

Document Path:          /
Document Length:        2 bytes

Concurrency Level:      20
Time taken for tests:   100.055 seconds
Complete requests:      1000
Failed requests:        0
Total transferred:      77000 bytes
HTML transferred:       2000 bytes
Requests per second:    9.99 [#/sec] (mean)
Time per request:       2001.099 [ms] (mean)
Time per request:       100.055 [ms] (mean, across all concurrent requests)
Transfer rate:          0.75 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    1   0.5      2       2
Processing:   101 1994  85.8   1999    2003
Waiting:      100 1138 569.8   1099    2002
Total:        101 1995  85.8   2001    2004
ERROR: The median and mean for the initial connection time are more than twice the standard
       deviation apart. These results are NOT reliable.

Percentage of the requests served within a certain time (ms)
  50%   2001
  66%   2001
  75%   2001
  80%   2001
  90%   2002
  95%   2002
  98%   2003
  99%   2004
 100%   2004 (longest request)

server.js

const http = require('http');
const { monitorEventLoopDelay } = require('perf_hooks');

const h = monitorEventLoopDelay({ resolution: 10 });
h.enable();

http.createServer(async (req, res) => {
  blockFor100ms();
  res.end('OK');
}).listen(3000)

function blockFor100ms () {
  let counter = 0
  while (counter++ < 10) {
    const start = Date.now()
    let i = 0
    while (Date.now() - start < 10) {
      i++
    }
  }
}

setInterval(() => console.log(h.mean / 1_000_000), 1_000);
setInterval(() => h.reset(), 60_000);