Connection timeouts in JEP 321 (HTTP Client)

[Chris Hegarty]

Clearly the request builder `timeout` method can be used to avoid
extremely long connection timeouts ( as demonstrated below ), but I see
Bernd's call for more fine grained control over various aspects of the
request.

I'm not opposed to an "HttpRequest.Builder.connectTimeout` method, but
this is coming very late in the JDK 11 development cycle. How important
is this for 11, given that the naked `timeout` can be used, somewhat, to
mitigate against long connection timeouts?


$ cat Get.java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpResponse.BodyHandlers;
import java.time.Duration;

public class Get {
  public static void main(String[] args) throws Exception {
    long before = System.nanoTime();
    try {
      HttpClient client = HttpClient.newHttpClient();
      HttpRequest request = HttpRequest.newBuilder(URI.create(args[0]))
            .timeout(Duration.ofSeconds(10))
            .build();
      HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
      System.out.println("response :" + response);
    } finally {
      System.out.println("elapsed secs :" + ((System.nanoTime() - before)/1000_000_000));
    }
  }
}
$ javac Get.java
$ java Get http://example.com:81
elapsed secs :10
Exception in thread "main" java.net.http.HttpTimeoutException: request timed out
   at java.net.http/jdk.internal.net.http.HttpClientImpl.send(HttpClientImpl.java:551)
   at java.net.http/jdk.internal.net.http.HttpClientFacade.send(HttpClientFacade.java:113)
   at Get.main(Get.java:17)

-Chris.

> On 24 Jul 2018, at 19:34, Markus Peloquin <markpeloquin at gmail.com> wrote:
> 
> Somebody pointed me at the upcoming HTTP client implementation, and I'm sad to see that connection timeouts are missing from the implementation (the old HTTP API). Is the absence of connection timeouts intended or an oversight? I'd like to see it added, and it looks like a simple change to me.
> http://openjdk.java.net/jeps/321
> http://mail.openjdk.java.net/pipermail/jdk-dev/2018-March/000996.html
> 
> There are some environments (such as AWS VPCs), where connection failures are only indicated by a connection timeout. This is because ICMP 'Destination Unreachable' packets are often not forwarded to the client (by load balancers, private links, etc) and there are supposedly some security concerns with allowing them by default. Those ICMP packets give immediate failures (net/host/protocol/port unreachable), but timeouts are slow.
> 
> The default timeout is unbounded in Java, though the TCP implementation of the OS times-out connection establishment to around 130 seconds.
> 
> It looks like the implementation uses SocketChannel, which still supports timeouts via chan.socket().connect(addr, timeout).
> 
> Markus