Thanks for the feedback everyone. Hi Alan, yes I can put some cycles into digging deeper with this one, as you point out there's probably more that needs doing. As Alex found running the new testcase 400 times it failed once still, interestingly during initial startListening() rather than the accept() where it was failing before. On a general issue of "thread-safety", I had a good look through the spec docs and architecture docs and couldn't find any specification of thread-safety(or not), should it be inferred if the docs don't specifically state "thread-safe" that it should be assumed as "not-thread safe"?
Thanks Andrew Andrew Leonard Java Runtimes Development IBM Hursley IBM United Kingdom Ltd internet email: andrew_m_leon...@uk.ibm.com From: Alan Bateman <alan.bate...@oracle.com> To: "serguei.spit...@oracle.com" <serguei.spit...@oracle.com>, Andrew Leonard <andrew_m_leon...@uk.ibm.com>, serviceability-dev@openjdk.java.net Date: 08/06/2019 10:12 Subject: Re: RFR JDK-8225474: JDI connector accept fails "Address already in use" with concurrent listeners On 08/06/2019 05:53, serguei.spit...@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 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
