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

[Alan Bateman]

On 08/06/2019 05:53, serguei.spitsyn at oracle.com wrote:
> Hi Andrew,
>
> It looks good to me.
> Thank you for your investigation and taking care about this!
I think this one needs further analysis as changing listenMap to be a 
CHM does not make this connector thread safe and doesn't address a 
number of other places where the map is accessed without 
synchronization. For example, startListening would need to be changed to 
use `putIfAbsent`, stopListening would need to use `remove` rather than 
get + remote. There are several others once you start looking at the 
sub-classes, e.g. SocketListeningConnector.updateArgumentMapIfRequired.

At the API level, JDI does not require connectors to be thread safe. I 
agree it is desirable for some of the connector implementations to be 
thread safe, particularly ListeningConnectors as an obvious usage will 
be for a listener thread to hand off a VirtualMachine to another thread.

Andrew - do you have cycles to investigate this further? I'm not opposed 
to changing the map to be a CHM but I think it needs further work.

-Alan