Hi Richard, welcome to net-dev! I'm sure you noticed already that the createNetworkInterface is only called when you set the system property java.net.preferIPv4Stack to true, or when you are on Windows 95/2000. In all other cases your code will use createNetworkInterfaceXP, which was fixed in JDK-14, see https://bugs.openjdk.org/browse/JDK-8225239.
If you're only interested in having that fix in JDK 8/11, check https://wiki.openjdk.org/display/JDKUpdates/JDK11u. If you're still interested in working on createNetworkInterface, read on. Going forward, we would want to keep only one implementation for each method, i.e. remove the non-XP methods, reimplement IPv4Stack using the XP methods, and remove the XP suffix. This would leave us with only one implementation to maintain. Spending any effort on improving the current non-XP version is probably a waste of time. I'm not sure if the next JDK release will support Win8, or if we only support Win10+ these days, but I'm pretty sure you can use the APIs available in Win8. HTH, DJ wt., 7 lut 2023 o 21:06 DiCroce, Richard <rich.dicr...@scientificgames.com> napisał(a): > > Hi everyone, > > I’d like to propose a patch to fix a performance issue with enumerating > network interfaces on Windows. The problem stems from the fact that getAll > calls createNetworkInterface for every interface, but does not pass the list > of interfaces that it has already collected. As a result, > createNetworkInterface gets the entire list all over again. > > > > When the number of interfaces is large, this can become very slow. On my > machine, there are almost 100 “interfaces” (most of which are really > filters). With the current code, a call to > NetworkInterface#getNetworkInterfaces() takes ~600 ms. My patch cuts it down > to ~15 ms. > > > > This is the first time I’ve tried to contribute to OpenJDK, so I’m looking > for someone to guide me through the process of getting this patch merged. > I’ve already gotten The Powers That Be at my company to sign the OCA. > > > > I’d also like to get your thoughts on a possible second patch that would be > more extensive and might contain some functional changes. The current code is > a little messy and uses some ancient APIs. Some initial experiments suggest > that newer APIs (available since Vista/Server 2008) would be faster. The > current code also invents its own interface naming scheme. Windows now has > APIs for that (e.g. ConvertInterfaceLuidToNameW), but switching to those > would obviously mean that getName() would return a different value than it > does today. getByName() would also need to be adjusted, but I could code it > such that it tries the Windows APIs first and then falls back to the existing > code, in order to minimize breakage. So, given those caveats, do you think > such a patch would have any chance of being accepted? Or would any breaking > changes be a no-go? > > > > Thanks, > > > > Rich DiCroce > > Senior Advanced Solutions Architect > > > > Scientific Games > > > > > > > > HAVE FUN. DO GOOD. PLAY HEALTHY. > > May be privileged. May be confidential. Please delete if not the addressee. > > > >
