Reinhold advocates adding fiber to your Java diet in Oracle Code One keynote
At last year’s JavaOne, Mark Reinhold, Chief Architect, Java Platform Group, introduced a forthcoming rapid release cadence in which a new version of Java would be produced every six months. The release train would always leave the station on time. If a planned feature wasn’t ready, it’d have to catch the next ride. It was an ambitious promise, especially given the fact that three years and six months separated the release of Java 8 and Java 9.
But despite being ambitious, the plan went off without a hitch. A year has passed since the original announcement, and in his Java language keynote at Oracle Code One, you could tell there was a bit of pride, if not subtle boasting, about the fact that the promise was kept. Java 10 and Java 11 were both released as planned in March and September of 2018.
“A moment of silence for Java 9 please – the last final massive JDK release.”
-Mark Reinhold, Chief Architect, Java Platform Group
Reinhold only briefly discussed some of the new features that got baked into the 2018 releases, with special emphasis on the fact that the rapid releases even included a significant language change, namely the inclusion of the var keyword. “Java 10 shipped on time in March of 2018, it contained merely 12 JEPs, but these weren’t trivial,” said Reinhold. “And Java 11 shipped just a few weeks ago. It contained 17 JEPs along with many bug fixes and enhancements.”
But you could tell that what Reinhold wanted to talk about most, which mapped nicely to what the audience was there to hear about, was the new features and facilities that the future of Java has in store. Reinhold highlighted four projects in particular, namely Amber, Loom, Panama and Valhalla.
According to Reinhold, Project Amber is all about rightsizing language ceremony. In this new era of machine learning and data driven microservices, it’s important for a developer to be able to express themselves clearly and concisely through their code. Project Amber attempts to address that, in a more meaningful way than simply templating boilerplate code.
In his keynote, Reinhold performed a batch of live coding, demonstrating the following three Project Amber features:
- Local variable type inference
- Raw string literals that don’t require escape sequencing, which is available as a preview feature in the JDK 12 early access release
- Switch expressions with enums and type inferences which will enhance case based conditional logic
Working with threads in Java has always been a bit of a mess in Java. From their useless priority settings to the meaningless ThreadGroup, the age old API leaves plenty of room for improvement. “Threads have a lot of baggage,” said Reinhold. “They have a lot of things that don’t make sense in the modern world. In fact, they have a lot of things that didn’t make sense when they were introduced.”
Demoing a recent build of Project Loom, Reinhold demonstrated how easy it is to implement concurrent threads using Fibers, much to the delight of every software developer who has ever struggled with I/O blocking and concurrency issues. A full implementation of this new, lightweight thread construct appears to only be a release or two away.
Panama is the isthmus that connects North and South America, while also providing a canal that connects the Atlantic with the Pacific. Add to that, a project about connecting native code written in languages like C++ and Go with what’s running on the JVM. Panama is about improving the connection between native code, foreign data and Java.
“Many people know the pain of JNI, the Java Native Interface,” said Reinhold. Project Panama promises to make integrating with libraries written in other languages not only easier, but capable of significantly increased performance over the frustratingly throttled JNI bridge.
As everyone who codes Java knows, the language will not scale linearly. The JDK will scale, which is why languages like Scala and Kotlin are so popular. But the manner in which Java uses pointers and mutable data means throwing twice as many resources at an application under heavy load will not result in anything near a doubling of the throughput. But all of that is about to change.
“Today’s processors are vastly different than they were in 1995. The cost of a cache miss has increased by a factor 200 and in some cases 1000. Processors got faster but the speed of light didn’t.”
-Mark Reinhold, Chief Architect, Java Platform Group
Project Valhalla introduces value types, a mechanism to allow the data used by Java programs to be managed much more efficiently at runtime. Value types are pure data aggregates that have no identity. At runtime, their data trees can be flattened out into a bytecode pancake. When Project Valhalla is finally incorporated into the JDK, the whole performance landscape will change.
“Chasing pointers is costly,” said Reinhold. Objects have identity, they can be attached to a sync monitor and they have internal state. When your applications create a massive numbers of objects, as do big data systems or artificial neural networks, the impact on performance can be significant.
Like all good magic tricks, Project Valhalla’s is deceivingly simple. All it requires is a single keyword, value, to be added to the class declaration, and this small addition completely changes an instance’s data is managed. There are of course small caveats that go along with the value keyword’s use, but that’s to be expected. In a live coding demonstration, Reinhold added the value keyword to a class that performed matrix calculations, and the result was almost a threefold increase in executed instructions per cycle, along with notable changes with regards to how memory was allocated and how garbage collection routines behaved.
The future of Java holds in store a number of impressive improvements that will make programming easier and the applications we create faster. And the great thing about the new rapid release cadence is the fact that we won’t have to wait for all of these things to be finalized before we get to use them. When features are complete, they’ll trickle their way into the upcoming release cycle, with many of these features only being one or two release cycles away.