Websocket connection closes without opening on Shotgun server - ruby

Question

I have a Sinatra app that uses Websockets.
My app works when I run it with ruby app.rb, but doesn't when I'm trying to run it with shotgun app.rb.
This is in my sending_out.erb:
<script>
$(document).ready(function(){
connection = new WebSocket('ws://' + window.location.host + window.location.pathname);
connection.onopen = function(){
$("#msgs").append('Connection opened'+"<br>")
};
connection.onmessage = function(e){
$("#msgs").append(e.data+"<br>");
};
connection.onclose = function() {
$("#msgs").append('Connection closes from view'+"<br>");
};
$("form").submit(function(){
connection.send( $("input").val() );
});
});
</script>
And this is in my app.rb:
require 'sinatra-websocket'
set :sockets, []
get '/sending_out' do
request.websocket do |connection|
connection.onopen do
connection.send("Hello World!")
settings.sockets << connection
connection.send("opened")
connection.send("went")
end
connection.onmessage do |msg|
EM.next_tick { settings.sockets.each{|s| s.send(msg) } }
end
connection.onclose do
warn("websocket closed")
settings.sockets.delete(ws)
end
end
end
It must show
Connection opened
Hello World!
opened
went
when I go to the page. But it only shows
Connection closes from view
with Shotgun.
And in the console it says WebSocket connection to 'ws://127.0.0.1:9393/sending_out' failed: Error during WebSocket handshake: Unexpected response code: 500.
Is there an issue running Websockets with Shotgun?

Answer 1

The main feature of Shotgun is that it automatically reloads your whole code every request and I think that could be also the problem you are facing.
Shotgun should be used just for development.
For production purposes you have plenty of other options available:
Puma
Rainbows
Unicorn
Thin
others
Comparison of ruby servers can be found on https://www.digitalocean.com/community/tutorials/a-comparison-of-rack-web-servers-for-ruby-web-applications