RFR: 8299813: java/nio/channels/DatagramChannel/Disconnect.java fails with jtreg test timeout due to lost datagram

[Aleksei Efimov]

On Wed, 26 Jun 2024 14:15:23 GMT, Daniel Fuchs <dfuchs at openjdk.org> wrote:

> Please find here a simple fix to solve an intermittent failure in  java/nio/channels/DatagramChannel/Disconnect.java
> 
> On some platform, the underlying system may allow two datagram sockets to bind to the same port, if one of them uses the wildcard address and the other doesn't.
> 
> What happens here is that during DC:connect, if the socket is unbound, it will get bound to the wildcard.
> From time to time, this results into binding to the same port that the `server` is using in the test.
> When that happens, datagram sent to the connected server may get misrouted and may not get delivered, and the call server::receive may block forever.
> 
> This change does two things: 
>   1. explicitly  bind the server to the loopback address instead of InetAddress.getLocalHost()
>   2. skip the receive part of the test if the client local address obtained after connecting uses the same port than the server. 
>   
> This is rare, and skipping the receive part in that case does not invalidate the test.

The changes look good to me.

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Marked as reviewed by aefimov (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19908#pullrequestreview-2147524606