Rack::Proxy#call method hangs

[amitfriedman12]

I have a custom class that overwrites the default Rack::Proxy functionality:

module Middleware
  class SOAProxy < Rack::Proxy

    attr_reader :app

    def initialize(app)
      @app = app
    end

    def call(env)
      if some_condition_is_met
        write_authorization_token(env)
        rewrite_proxy_host(env, proxy_host)
        rewrite_request_path(env)
        super(env)
      else
        app.call(env)
      end
    end

However I am having an issue that occurs when the super(env) code gets executed.
Even after the local server which i hit with my API call returns a 200 response, the call method does not finish executing for another 5-10 seconds or so.

After looking into it, this is where the API call is made and where the hanging occurs.
I would expect the call the http request to finish executing as soon as the local server returns the 200 response, but instead the code continues executing a few seconds later.

Any ideas how to further debug this?
Using rails 3.2.16 and ruby 2.3.3.

[velles]

Few more details on this issue:

1. Fast Proxy - respond immediately after the targeting server is done - Rails 3.2.16 proxies to Rails
   4 with puma server
2. Slow Proxy - respond takes 20-30s after the targeting server is done - Rails 3.2.16 proxies to
   Rails 5 API with puma server

[kenzan100]

Did you guys find out what was the issue here?

[kenzan100]

#fyi for my case it was related to the header Connection: KeepAlive as per axsuul/rails-reverse-proxy#34