Added HTTP::Server.run method

[aurimasniekis]

Hi, today I just discovered the Crystal language and was amazed with performance of HTTP server.

I was trying to implement the fork model based multi process HTTP server but I ran into the problem that once you start listen to the TCPServer I am unable to fork anymore so I add one more method to allow use HTTP::Server.bind & HTTP::Server.run to make possible fork the process and then start accepting connections.

Here is my small code example I was trying to test

require "http"

server = HTTP::Server.new(3000) do |context|
  context.response.content_type = "text/plain"
  context.response.print "Hello world, got #{Process.pid}!"
end

server.bind

puts "Listening on http://127.0.0.1:3000"

process = nil
4.times do |i|  
  process = Process.fork

  if (nil == process)
    server.run
    exit
  end
end
  
process.as(Process).wait()

Here is performance difference between single process and 4 process.

Running 20s test @ http://127.0.0.1:3000/
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.35ms  425.43us  10.29ms   76.25%
    Req/Sec    37.04k     5.02k   51.45k    61.00%
  1474238 requests in 20.01s, 156.06MB read
Requests/sec:  73663.69
Transfer/sec:      7.80MB

Running 20s test @ http://127.0.0.1:3000/
  2 threads and 100 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.13ms  360.19us  15.57ms   85.06%
    Req/Sec    44.28k     5.57k   50.56k    70.75%
  1761893 requests in 20.01s, 186.51MB read
Requests/sec:  88032.69
Transfer/sec:      9.32MB

Difference is not so big as I was only running 2 threads but still really not bad improvement and ability to extend HTTP server to work bit differently then intended.

P.S. I am yet not much familiar with project so if I miss something please tell me I will try to help.
P.P.S I opened this pull request as open discussion on this topic.

[sdogruyol]

Welcome to Crystal community @aurimasniekis, congrats on your first PR 🎉

[ysbaddaden]

What about first bind, then fork and call listen in them. This will reuse the TCPServer internally.

server.bind

4.times do
  fork do
    server.listen
  end
end

sleep

[aurimasniekis]

I think it's possible as far as I see as I am less than 24h with Crystal still reading docs... 👍

[asterite]

I'm closing this because the solution given by @ysbaddaden accomplishes this