what triggers the error

[binarytracer]

Im currently benchmarking an Express App,

benchmark.js

const http = require('http');
const autocannon = require('autocannon');

function handle(req, res) {
  res.end('hello world');
}

function startBench() {
  function finishedBench(err, res) {
    console.log('finished benchmarking');
    // console.log('finished bench', err, res);
  }

  const config = {
    url: 'http://localhost:3000/596c473a12288a0bd490a517',
    amount: 6000,
  };
  const instance = autocannon(config, finishedBench);

  instance.on('reqError', (...args) => {
    console.log('---------------------');
    console.log(args);
    console.log('---------------------');
  });

  autocannon.track(instance, { renderResultTable: true });

  // this is used to kill the instance on CTRL-C
  process.once('SIGINT', () => {
    instance.stop();
  });
}

const server = http.createServer(handle);

server.listen(0, startBench);

round 1

STAT	AVG	STDEV	MAX
Latency (ms)	44.94	3.52	96
Req/Sec	214.29	24.89	225
Bytes/Sec	149 kB	17.3 kB	164 kB

6k requests in 28s, 4.18 MB read

---

round 2

  const config = {
    url: 'http://localhost:3000/596c473a12288a0bd490a517',
    connections: 6000,
    timeout: 60,
    amount: 6000,
  };
  const instance = autocannon(config, finishedBench);

STAT	AVG	STDEV	MAX
Latency (ms)	4822.17	2061.34	9641
Req/Sec	493.37	581.35	1600
Bytes/Sec	346 kB	410 kB	1.18 MB

5k requests in 12s, 3.78 MB read 573 errors (573 timeouts) finished benchmarking

Error logging

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I would like to know what causes it to trigger errors / timeout?

[mcollina]

timeout: the number of seconds we wait for a response to arrive. We wait 10 by default. This is consistent with the MAX latency you are seeing, 9 seconds. Some requests go over.

errors: timeout plus other errors, like 500.

[binarytracer]

Thanks, @mcollina

just updated my post.

knowing that kind of situation, what needs to be done? Do i need to to adjust the express application or i need to adjust autocannon configuration?

[mcollina]

The bug is in the express application.

[GlenTiki]

You can adjust the timeout period to be larger if you want to see what the max delay is without a timeout. Check the readme for how to do this. However a 10 second+ latency/response delay is probably not what you want for your application anyway, so I would advise you to keep treating it as an error :)

[binarytracer]

thanks @thekemkid and @mcollina, :thumbsup: this npm works great.