RFR JDK-8225474: JDI connector accept fails "Address already in use" with concurrent listeners

[Alan Bateman]

On 13/06/2019 20:18, Andrew Leonard wrote:
> Thanks Alex, good spot.
> I have done all the changes now with the latest updates, and have 
> performed some stress tests on xLinux, Win64 and Mac64, all successful.
>
> Please can I get reviews and sponsor for webrev.04:
> http://cr.openjdk.java.net/~aleonard/8225474/webrev.04/
Retrofitting code that wasn't developed to be used by multiple 
concurrent threads to be thread safe takes time and will require a lot 
of review effort. I don't have time to spend on this now and I suspect 
this one will need a second reviewer to help with the confidence that 
you've got everything.

Things to check are:

- ConnectorImpl::toString iterates over the values in defaultArguments, 
I assume this will require synchronization

- ConnectorImpl.trueString and falseString are initialized lazily 
without synchronization. It might be okay but a comment to explain why. 
Ditto for the lazily initialization of the messages field in getString.

- All but the "value" field in the Connector.Argument implementations 
should be final. It might be that the value fields need to volatile 
(needs more study).

- GenericListeningConnector fields should be final. You can also 
initialize listenMap with new ConcurrentHashMap<>() .

- GenericListeningConnector.accept needs further analysis, at least for 
the case where the debugger hasn't called startListening.

There may be more issues, it just needs time to walk through the 
original implementation.

-Alan

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