RFR: 8350279: HttpClient: Add a new HttpResponse method to identify connections [v6]

[Jaikiran Pai]

On Fri, 4 Apr 2025 15:27:25 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

>> test/jdk/java/net/httpclient/HttpResponseConnectionLabelTest.java line 412:
>> 
>>> 410:         HttpResponse<String> response1 = client.send(pair.request, BodyHandlers.ofString(CHARSET));
>>> 411:         LOGGER.log("Firing request 2...");
>>> 412:         HttpResponse<String> response2 = client.send(pair.request, BodyHandlers.ofString(CHARSET));
>> 
>> In theory, there's no guarantee that these sequential requests will be executed "immediately" one after the other. Internally, in the httpclient implementation, we use idle timeouts to close idle connections. So I'm wondering if it's realistic that there would ever be a case where in some setup (like the CI), these two execute so far apart from each other (`-Xcomp`?) that the connection might have timed out in the meantime and closed? Thus the second request ends up using a different connection and fails this test?
>> Should we perhaps use `othervm` for this test and configure an extremely high idle timeout of connections, through the system properties, to avoid such intermittent failures?
>
> Good point - our default idle timeout is 30s IIRC. There would need to be a pause of 30s between the two calls to `client.send` however. Not impossible but unlikely. We could either pass a higher timeout (with e.g. `-Djdk.httpclient.keepalive.timeout=120`) preemptively, or wait until we see the test fail...

Waiting for the test to fail due to this reason and then adjusting the timeout is fine with me.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24154#discussion_r2029126877