RFR: 8297778: Modernize and improve module jdk.sctp [v5]

[Alan Bateman]

On Thu, 1 Dec 2022 14:02:51 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> > > receiverThread and senderThread are declared volatile but are always accessed (r/w) whilst synchronising on the stateLock.
> 
> @stsypanov Yes I am aware that this was a separate observation which is not related to the assignment of the variables. I can surely keep them volatile but I wonder why they are volatile in the first place.

The SCTP implementation dates from JDK 7 and has not changed much since then.  In the case of the thread IDs used for signalling then I suspect this was copied from the original SocketChannelImpl code that has been replaced/re-written by way of splitting the blocking and non-blocking code paths (the thread IDs are only needed for channels configured blocking). If all access to the thread IDs is guarded by stateLock then you should be okay to making it non-volatile. Testing is a challenge when touching this area as SCTP requires special kernel configuration. Keeping the changes simple and easy to review would be helpful.

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PR: https://git.openjdk.org/jdk/pull/11418