3.x: Target Java version

Java 9 has recently been released with a couple of properties that can affect the next RxJava version’s design:

Pros:

• Less memory use due to VarHandles: no more need for AtomicXXX class indirection
• New standard Reactive-Streams interoperation point java.util.concurrent.Flow
• Ability to prevent certain RxJava internal resource leaks via java.lang.ref.Cleaner
• Lambda usage in unit tests

Cons:

• VarHandles are reflection based, the ProGuard woes come back.
• May take several years Java 9 level API to become mainstream enough on the Android platform.
• Need for Gradle 4+ and the replacement of the now unsupported rxjava-nebula plugin. We successfully switched to Gradle and dropped that plugin.

[akarnokd]

I decided RxJava 3.x will remain a single Java 6 supporting library. Since Android moves away from Java towards Kotlin and Project Reactor & Spring will keep up with Java, there is no real need to bump up the minimum requirement for the time being.

[mattwelke]

See https://github.com/reactive-streams/reactive-streams-jvm/issues/394#issuecomment-335982956’s excellent blog post.

Any chance there’s a working link to this blog post? I’m just now learning about reactive programming in Java, getting confused about why there are so many libraries, and this sounds like it’d be a good read. That link results in a Ghost error right now.