How to disable TCP-port sharing in vert.x 2.0.0?

[Nikolay Artamonov]

I run two instances of my application (inside diffirent JVMs) with embedded vert.x. Each instance tries to create HttpServer and bind to some port and host:

Vertx vertx = VertxFactory.newVertx();

HttpServer server = vertx.createHttpServer().requestHandler(handler);

server.listen(port, host);

When I used vert.x 1.2.3 last call (HttpServer#listen) was throwing exception with cause java.net.BindException if `port` was already used by other instance of application. After upgrade to vert.x 2.0.0 it doesn't happen anymore. I suppose it's because of how scaling works in new version of vert.x.

How can I determine that some port is already used by other instance of application?

Thanks!

[Tim Fox]

On 18/08/13 07:40, Nikolay Artamonov wrote:
> I run two instances of my application (inside diffirent JVMs) with embedded
> vert.x. Each instance tries to create HttpServer and bind to some port and
> host:
>
> Vertx vertx = VertxFactory.newVertx();
> HttpServer server = vertx.createHttpServer().requestHandler(handler);
> server.listen(port, host);
>
> When I used vert.x 1.2.3 last call (HttpServer#listen) was throwing
> exception with cause java.net.BindException if `port` was already used by
> other instance of application. After upgrade to vert.x 2.0.0 it doesn't
> happen anymore.

In 2.0, any bind exception will be provided to you in the
Handler<AsyncResult> that you provide to the listen method.

[Nikolay Artamonov]

Yes, I tried it. Unfortunately, AsyncResult is always succeeded, even if port was already binded by some other application instance. So I get no bind exception when run two instances (inside different JVM) of application with following source code (Scala). 

import org.vertx.java.core.{AsyncResult, VertxFactory, Handler, Vertx}

import org.vertx.java.core.http.{HttpServer, HttpServerResponse, HttpServerRequest}

object Main extends App {

  val server = VertxFactory.newVertx().createHttpServer().requestHandler(handler)

  server.listen(88, "localhost", new Handler[AsyncResult[HttpServer]] {

    def handle(res: AsyncResult[HttpServer]) {

      res.succeeded() match {

        case true  => println("Server was binded to port 88.")

        case false => res.cause().printStackTrace()

      }

    }

  })

  System.in.read()

  def handler = new Handler[HttpServerRequest] {

    def handle(req: HttpServerRequest) {

      println("REQ %s: %s (server ID=%s)".format(req.method(), req.uri(), this.##))

      req.response().setStatusCode(200)

      req.response().end()

    }

  }

}

[Tim Fox]

It's impossible to bind two server sockets to the same host:port- this
is not a Java limitation, or a Vert.x limitation, it's just how TCP
sockets work.

Vert.x doesn't do any port sharing between different Vert.x instances.

[Nikolay Artamonov]

I know it. I don't claim that vert.x can actually share TCP port that is not possible. What I claim that two adjacent calls to HttpServer#listen() with same port and host does not throw bound exception (or any other exception), synchronously or asynchronously. Is it correct contract for method HttpServer#listen()?

воскресенье, 18 августа 2013 г., 15:34:53 UTC+4 пользователь Tim Fox написал:

[Tim Fox]

On 19/08/13 19:54, Nikolay Artamonov wrote:
> I know it. I don't claim that vert.x can actually share TCP port that is
> not possible. What I claim that two adjacent calls to HttpServer#listen()
> with same port and host does not throw bound exception (or any other
> exception), synchronously or asynchronously. Is it correct contract for
> method HttpServer#listen()?

The second one to listen should fail.

Can you provide a runnable test case that demonstrates the issue (not in
Scala please)?
>
> О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫, 18 О©╫О©╫О©╫О©╫О©╫О©╫О©╫ 2013 О©╫., 15:34:53 UTC+4 О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫О©╫ Tim Fox
> О©╫О©╫О©╫О©╫О©╫О©╫О©╫:

[Nikolay Artamonov]

Can you provide a runnable test case that demonstrates the issue (not in
Scala please)?

Yes, of course: https://gist.github.com/nartamonov/215ae1c2fc22dc0f57a6

Thanks!

[Tim Fox]

Vert.x allows you to bind multiple servers in the same Vert.x instance
to the same host/port - under the bonnet only one server is created and
requests are round robin'd between them. This is explained in the API
manual.

So I would your test to fail.

[Tim Fox]

On 23/08/13 18:46, Tim Fox wrote:

Vert.x allows you to bind multiple servers in the same Vert.x instance to the same host/port - under the bonnet only one server is created and requests are round robin'd between them. This is explained in the API manual.

http://vertx.io/core_manual_java.html#scaling-tcp-servers

The link is for TCP but the same applies for HTTP servers

[Nikolay Artamonov]

Thanks, Tim! If I understand you correctly, you said that multiple HttpServers in the same vertx instance can be bound to the same port/host. But in my test I actually create two different non-clustered vert.x instances (according to javadocs) with this call:

VertxFactory.newVertx()

Am I missing something or don't understand? Is it correct that that two HttpServers in different vertx instances can be bound to the same port/host? If so, how can I disable such load balancing behaviour?

2013/8/23 Tim Fox <timv...@gmail.com>

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mailto:narta...@gmail.com

[javajosh]

On Friday, August 23, 2013 11:50:12 AM UTC-7, Nikolay Artamonov wrote:

Thanks, Tim! If I understand you correctly, you said that multiple HttpServers in the same vertx instance can be bound to the same port/host. But in my test I actually create two different non-clustered vert.x instances (according to javadocs) with this call:

VertxFactory.newVertx()

Am I missing something or don't understand? Is it correct that that two HttpServers in different vertx instances can be bound to the same port/host? If so, how can I disable such load balancing behaviour?

Your test is creating two verticles in one vertx instance. Therefore they are sharing ports.

A proper test would require the use of two processes. E.g. something like this:

===test.sh===

echo 'vertx.createHttpServer().requestHandler {req ->"got a request!"}.listen(8080) ; println "listening on 8080"' > foo.groovy

vertx run foo.groovy &

vertx run foo.groovy 

This will yield:

ERROR: transport error 202: bind failed: Address already in use

[Tim Fox]

Nikolay - can you add an issue in Bugzilla?

Thanks

On 23/08/13 19:50, Nikolay Artamonov wrote:
> Thanks, Tim! If I understand you correctly, you said that multiple

> HttpServers *in the same vertx instance* can be bound to the same
> port/host. But in my test I actually create *two different non-clustered
> vert.x instances* (according to
> javadocs<http://vertx.io/api/java/org/vertx/java/core/VertxFactory.html#newVertx()>)

> with this call:
>
> VertxFactory.newVertx()
>
> Am I missing something or don't understand? Is it correct that that two

> HttpServers in *different* vertx instances can be bound to the same