Many extra connections when running WebSocket server or client.

From: Weiqi Gao <weiqigao_at_gmail.com>
Date: Thu, 09 May 2013 16:05:25 -0500

Hi,

When I start a simple HttpServer using Grizzly, like this:

     import org.glassfish.grizzly.http.server.HttpServer;
     import java.io.IOException;

     public class JustHttpServerMain {
         public static void main(String[] args) throws IOException {
             HttpServer server = HttpServer.createSimpleServer(".", 8080);
             server.start();
             System.in.read();
         }
     }

I see the Java process listening on port 8080, which is what I expect,
and 8 additional connections that the process makes to itself. Here's
the output of "netstat -anto | grep 9536" (where 9536 is the pid):

$ netstat -anto | grep 9536
   TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 9536 InHost
   TCP 127.0.0.1:49339 127.0.0.1:49340 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49340 127.0.0.1:49339 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49341 127.0.0.1:49342 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49342 127.0.0.1:49341 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49343 127.0.0.1:49344 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49344 127.0.0.1:49343 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49345 127.0.0.1:49346 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49346 127.0.0.1:49345 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49347 127.0.0.1:49348 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49348 127.0.0.1:49347 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49349 127.0.0.1:49350 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49350 127.0.0.1:49349 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49351 127.0.0.1:49352 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49352 127.0.0.1:49351 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49353 127.0.0.1:49355 ESTABLISHED
9536 InHost
   TCP 127.0.0.1:49355 127.0.0.1:49353 ESTABLISHED
9536 InHost
   TCP [::]:8080 [::]:0 LISTENING 9536 InHost

This is on a Windows 7 Pro SP1 environment with 64-bit Oracle JDK 1.7.0_21.

Am I the only one who gets the extra connections? If this is something
that is known, is there an explanation (or a fix) for it?

Thanks,

--
Weiqi Gao
weiqigao_at_gmail.com
http://weiqigao.blogspot.com/