Can we start with making Pulsar is able to run with both Java 8 and Java 11?
Because I think there are still a lot of users running with Java 8. - Sijie On Mon, Feb 8, 2021 at 2:32 AM Enrico Olivelli <eolive...@gmail.com> wrote: > Hello Pulsar community, > I would like to start a discussion about Java 11 support and about dropping > support for JDK8 on the server side. > It will take time, see my points below. > > At the moment we have these use cases about Java compatibility: > - Java client users > - Building Pulsar and running Pulsar tests > - Server users that use the binary tarball > - Apache Pulsar Docker images consumers > > I have been running in production BookKeeper and Pulsar on modern JDKs > (Java version > 8) for much time and I see that there are no issues at > least for the scenarios I have seen. > > JDK11 is currently referred to as LTS by major vendors (for whatever it > means, please do not enter a "Java LTS thread", there are plenty of threads > about what is Java LTS about) and Java 17 is coming. > I expect that any of the new users will start running on JDK11 (and > probably on JDK15 for the early adopters) if they do not want to pay for > JDK8 support > > Also the latest versions of Presto require Java 11 to run, if we do not > move to Java 11 we won't be able to upgrade Presto. > > This is what I expect on the mid term (after 2.8): > > 1) Java Clients: stick to JDK8 compatibility > I believe that on the Java client side we should stick to JDK8 > compatibility, because unfortunately JDK8 is still a version that is widely > used in the industry. > In order to ensure JDK8 compatibility we have useful tools: > - there are Maven plugin that ensure that we are not producing and > consuming third party libraries that are not compatible with JDK8 > - we can add one (or more) Maven modules that run on CI using JDK8 and > consume the artifacts produced by the build > > 2) Building Pulsar and running Tests > We can require Pulsar to be built on JDK11. > We can set maven.compiler.release to 11 in generale and > maven.compiler.release to 8 for all of the modules that concur to build up > the Java client > Tests will run on JDK11 on CI. > We could desire to run the Pulsar client tests on JDK8, but many of them > are indeed inside the pulsar-broker module. > > 3) Server users that use the binary tarball > We will have to announce that from Pulsar 2.x (2.8 or 2.9?) Pulsar server > side components will require JDK11 > The same applies to users that run Pulsar broker by starting it from the > Jars deployed to Maven central. > > 4) Docker images consumers: > This is easy, just change the images in order to use JDK11. > > > I believe that enforcing JDK11 on the server side side is a big move and we > should announce it with care and let users prepare for this jump. > > So in the meantime we could start with a soft transition plan, starting for > 2.8 release: > - Build Pulsar on JDK11 and run CI on JDK11 > - Set maven.compiler.release to JDK8 > - Change docker images to JDK11 > > This way: > - consumers of the Java client will be able to run on JDK8 > - consumers of the Binary tarballs for the server will be able to run on > JDK8, say for Pulsar 2.8 > - consumers of Docker images will start to enjoy JDK11 > - Pulsar developers will get used to having JDK11, but they won't be able > to leverage JDK11 language and JRE features (only faster runtime, GC....) > > I can start a PIP, but I believe a little discussion on the ML is a good > starting point. > > Thoughts ? > Enrico >
