Benchmark PM2 vs HAPROXY vs NGINX - Simple HTTP Node.js application

cat proc-cpuinfo

processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 61
model name	: Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz
stepping	: 4
microcode	: 0x23
cpu MHz		: 2457.468
cache size	: 3072 KB

haproxy TCP Stream mode to 4 apps

>>> wrk -c 100 http://localhost:6001
Running 10s test @ http://localhost:6001
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     4.43ms    4.50ms  56.72ms   86.00%
    Req/Sec    14.50k     2.31k   18.41k    89.50%
  288589 requests in 10.01s, 34.40MB read
Requests/sec:  28837.34
Transfer/sec:      3.44MB

haproxy.cfg

global
  maxconn 20000

frontend http-frontend
  mode tcp
  bind *:6001
  default_backend http-backend

backend http-backend
  mode tcp
  balance roundrobin
  server http-instance-0 localhost:8001 maxconn 20000
  server http-instance-1 localhost:8002 maxconn 20000
  server http-instance-2 localhost:8003 maxconn 20000
  server http-instance-3 localhost:8004 maxconn 20000

http.js

var http = require('http');

var server = http.createServer(function(req, res) {
  res.writeHead(200);
  res.end('hey');
}).listen(8000, function() {
  console.log('Listening on %s', server.address().port);
});

nginx TCP Stream to 4 apps

>>> wrk -c 100 http://localhost:7001
Running 10s test @ http://localhost:7001
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     3.94ms    2.55ms  44.78ms   93.74%
    Req/Sec    13.61k     1.57k   16.67k    90.00%
  270752 requests in 10.02s, 32.28MB read
Requests/sec:  27011.39
Transfer/sec:      3.22MB

nginx.conf

worker_processes  5;  ## Default: 1
daemon off;

events {
  worker_connections  4096;  ## Default: 1024
}

stream {
   server {
      listen     7001;
      proxy_pass apistream;
   }

   upstream apistream {
      server 127.0.0.1:8001;
      server 127.0.0.1:8002;
      server 127.0.0.1:8003;
      server 127.0.0.1:8004;
    }
}

pm2 start http.js -i max

>>> wrk -c 100 http://localhost:8001
Running 10s test @ http://localhost:8001
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     3.62ms    7.83ms 225.85ms   97.73%
    Req/Sec    17.79k     2.80k   21.40k    85.50%
  354083 requests in 10.01s, 42.21MB read
Requests/sec:  35387.79
Transfer/sec:      4.22MB

listen(8000, function()

shouldn't this value changed based on certain parameters? (env variable, etc.)

https://gist.github.com/Unitech/f56f3c3135631c14355bdca791d5eba4