RFR: 8219804 ava/net/MulticastSocket/Promiscuous.java fails intermittently due to NumberFormatException

[Chris Hegarty]

Michael,

On 21/06/2019 11:53, Michael McMahon wrote:
> Small test case update. The test has failed a couple of times where it 
> appears
> to be receiving input on a multicast socket which could not be generated 
> by the test case itself.
> The test happens to use multicast groups that are assigned by IANA, and 
> globally routable.
> So, it is conceivable that other entities are sending packets picked up 
> by the test.
> The test also does not protect against other instances of itself running 
> on different hosts
> at the same time, though that doesn't seem to be the cause of this failure.
> The change is to use non-routable multicast groups and to add some 
> hopefully unique data
> to the test in case the test might be running on multiple hosts on the 
> same subnet simultaneously.
> 
> http://cr.openjdk.java.net/~michaelm/8219804/webrev.1/index.html

I think this is ok.

With this change, the negative scenarios ( that are expected to
timeout ), are susceptible to retrying when/if rogue packets are
received ( I guess this is less likely now, since the groups are
non-routable ). Would it be helpful to just print out the ignored
packet / data ( in case of future reliability issues )?

There is a nio test, java/nio/channels/DatagramChannel/Promiscuous.java
that follows a similar pattern. Should it be updated in a similar way?

-Chris.