Hi Alan, Thanks for your reply.
On Thu, 2025-09-18 at 12:30 +0100, Alan Bateman wrote: > > On 18/09/2025 08:36, Geliang Tang wrote: > > > > > I have completed the implementation. Thanks to Xiang Gao and Gang > > Yan > > for their help. I added a new option named TCP_MPTCPIFY in > > jdk.net.ExtendedSocketOptions (the name was chosen to align with > > 'mptcpize' tool in mptcpd and 'mptcpify' in BCC). When this option > > is > > set, it calls the JNI function mptcpify0. > > > > Following your suggestion, mptcpify0 is implemented by referencing > > Java_sun_net_sdp_SdpSupport_convert0. It creates a new MPTCP > > socket, > > uses dup2 to duplicate it, and then closes the redundant socket. > > > > I have added your tag in the patch: > > > > Suggested-by: Alan Bateman <[email protected]> > > > > I also included a test example for this option. All modifications > > can > > be found here: > > > > https://github.com/openjdk/jdk/compare/master...geliangtang:jdk:master > > > > Please provide any feedback or suggestions. As for the next steps, > > should I create a new issue for this feature and submit a proper > > pull > > request? > > > > Thanks for confirming that the direction suggested works. This at > least demonstrates a feasible direction that does not impact the > standard API. > > As regards next steps then I think start a thread on net-dev to try > to get input. I think it would be useful to show potential scenarios > where it would be useful and what performance benefits might come > from it. I think also useful to talk about whether this is something > that an application has to opt into, maybe there are other > configuration approaches that would not require application changes? > > I think it would be useful to discuss testing. If this feature were > integrated into the JDK then how would it be tested? Who would test > and maintain it? There is a JDK release every 6 months, is someone > going test it with each release? > > If it goes ahead then there the name of the extended socket option > and its API docs will need discussion. Details around state will need > to be specified, would it be supported to set TCP_MPTCP when bound or > connected, does it make sense to ever attempt to set it to false > after setting it to true (these are just examples of the details that > will need to be specified, they are not important right now). Following your suggestion, I have started a new thread on net-dev: Add Extended MPTCP (Multipath TCP) Socket Option Support to OpenJDK https://mail.openjdk.org/pipermail/net-dev/2025-September/028085.html Thanks, -Geliang > > -Alan. > >
