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

[David Holmes]

+1 from me.

What thread-safety should mean here needs to be defined.

David

On 8/06/2019 7:11 pm, Alan Bateman wrote:
> 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