RFR: 8371629: Add diagnostic output IPSupport.printPlatformSupport(System.out) to tests in java/nio/channels directory -- part I

[Mark Sheppard]

On Thu, 20 Nov 2025 14:29:46 GMT, Alan Bateman <alanb at openjdk.org> wrote:

> I have my doubts on the usefulness of this as IPSupport.printPlatformSupport doesn't print the network configuration. If there is dynamic reconfiguration going on (and I agree that is hard to diagnose) then dumping the network configuration in the jtreg failure handler would be useful if it's not there already.

Yes, the network configuration is printed in the jtreg handler. BUT, wrt this addition, we are not looking for network configuration (at this juncture). We wish to determine what is the "perception" of the JDK runtime, used in the test, wrt IPv4 and IPv6 support and correlate that with the configuration i.e. IPv6 only. Has it created a socket in the correct  domain etc., has the OS been (accidentally) altered to enable IPv4, while it may not have it configured. If preferIPv4Stack is set true, why has a test not failed.

Additionally, this is not just for failures. It is also to allow review of successful test execution, and to ensure the consistency of behaviour within IPv6 only environments.

Prior to running test in IPv6 only environments, we run a set of sanity checks, which are set standalone tests verifying the configured environments. We capture the network configuration for comparison with the jtreg failure capture. 

We do a lot of preparation to ensure the env are setup correctly. But anomalies have been observed, which have raised question on the veracity of the tests. 

This change is to assist in evaluating the test JDK runtime thinks it is using and what has been configured.

It's a small addition which goes a long way to helping the analysis

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PR Comment: https://git.openjdk.org/jdk/pull/28420#issuecomment-3558633339