Highlights from Java 10, 11 and 12 and Future of Java Javaland by Vadym Kazulkin, ip.labs GmbH

Transcription

1 Highlights from Java 10, 11 and 12 and Future of Java Javaland by Vadym Kazulkin, ip.labs GmbH

2 Contact Vadym Kazulkin, ip.labs GmbH (Meetup)

3 ip.labs GmbH

4 Agenda Highlights from Java 10 Highlights from Java 11 Highlights from Java 12 Project Amber (Simplifying syntax) Project Valhalla (Value Types and Specialized Generics) Project Metropolis (Polyglot GraalVM) Project Loom (Fibers and Continuations)

5 Highlights from Java 10

6 JEP 286 (Project Amber) Local-Variable Type Inference URL url = new URL( ); URLConnection connection = url.openconnection(); Reader reader = new BufferedReader ( new InputStreamReader(connection.getInputStream())); var url = new URL( ); var connection = url.openconnection(); var reader = new BufferedReader ( new InputStreamReader(connection.getInputStream()));

7 JEP 304 Garbage Collector Interface Goals: Better modularity for HotSpot internal GC code Make it simpler to add a new GC to HotSpot without perturbing the current code base Make it easier to exclude a GC from a JDK build

8 JEP 317 Experimental Java-Based JIT Compiler Graal, a Java-based JIT compiler on the Linux/x64 platform, is the basis of the experimental Ahead-of-Time (AOT) compiler introduced in JDK 9. To Enable: -XX:+UnlockExperimentalVMOptions -XX:+UseJVMCICompiler

9 Miscellaneous API Changes Better container-awareness Before later versions of Java 8 Runtime.getRuntime().availableProcessors() -> retrieves value from sysconf, means the total number of processors for VM Runtime.getRuntime().maxMemory() -> gets the value for VM overall memory Java 9 is container-aware automatically detecting cpusets JVM considers cgroups memory limits if the following flags are specified: -XX:+UseCGroupMemoryLimitForHeap -XX:+UnlockExperimentalVMOptions Max Heap space will be automatically set (if not overwritten) to the limit specified by the cgroup Sources: Improve docker container detection and resource configuration usage Better containerized JVMs in JDK 10

10 Miscellaneous API Changes Better container-awareness For fixing CPU shares in Java 9 overwrite -XMX for memory -XX:ParallelGCThreads and -XX:ConcGCThreads for CPU -System property java.util.concurrent.forkjoinpool.common.parallelism for ForkJoinPool Better container-awareness in Java 10 (CPU shares support is included) Runtime.getRuntime().availableProcessors() Runtime.getRuntime().maxMemory() Sources: Java SE 9 support for Docker CPU and memory limits Nobody puts Java in a container

11 Miscellaneous API Changes java.util.list/set/map.copyof(collection) java.util.stream.collectors.tounmodifiablelist/set/map(stream) Optional.orElseThrow()

12 Highlights from Java 11

13 JEP 323 (Project Amber) Local-Variable Syntax for Lambda Parameters (x, y) -> x.process(y) // implicitly typed lambda expression (var x, var y) -> x.process(y) // implicit typed lambda expression var var y) -> x.process(y)

14 JEP 321 HTTP Client Goals: Standardize the incubated HTTP Client API introduced in JDK 9, via JEP 110, and updated in JDK 10 HTTP 2.0 Support

15 JEP 332 Transport Layer Security 1.3 Goal: Implement version 1.3 of the Transport Layer Security (TLS) Protocol

16 Miscellaneous API Changes File.isSameContents() in addition to File.isSameFile() New methods and behaviour on the Java String class String#trim method : uses the definition of space as any codepoint that is less than or equal to the space character codepoint (\u0040.) String#lines and String#strip also use this definition of String#trim method String#isBlank : true if the string is empty or contains only white space String#stripLeading, String#stripTrailing : removal of Unicode white space from the beginning/end String#repeat(int numberoftimes) : repeat a string given number if times Sources:

17 Highlights from Java 12

18 JEP 2 Preview Language and VM Features Goals: A preview language or VM feature is a new feature of the Java SE Platform that is fully specified, fully implemented, and yet impermanent. It is available in a JDK feature release to provoke developer feedback based on real world use On JDK 12: javac Foo.java // Do not enable any preview features javac --release 12 --enable-preview Foo.java // Enable all preview features of Java SE 12 javac --release 11 --enable-preview Foo.java // DISALLOWED On JDK 13: javac Foo.java // Do not enable any preview features javac --release 13 --enable-preview Foo.java // Enable all preview features of Java SE 13 javac --release 12 --enable-preview Foo.java // DISALLOWED

19 JEP 325 Switch Expressions (Preview) int numberofletters; switch(season) { case FALL: numberofletters=4; break; case WINTER: case SPRING: case SUMMER: numberofletters=6; break; default: throw new IllegalStateException( unknown season +season); }

20 JEP 325 Switch Expressions (Preview) int numberofletters =switch(season) { case FALL -> 4; case WINTER, SPRING, SUMMER -> 6; };

21 JEP 230 Microbenchmark Suite Goal: Add a basic suite of microbenchmarks based on the Java Microbenchmark Harness (JMH) to the JDK source code, and make it easy for developers to run existing microbenchmarks and create new ones.

22 JEP 189 Project Shenandoah: Low-Pause-Time GC (Experimental) Goals : ultra-low pause time garbage collector that reduces GC pause times by performing more garbage collection work concurrently with the running Java program CMS and G1 both perform concurrent marking of live objects. Shenandoah adds concurrent compaction Sources: Talk by Alexey Shipilev: Shenandoah: The Garbage Collector That Could

23 Miscellaneous API Changes Double result = Stream.of(1, 2, 3, 4).collect(teeing( summingdouble(i -> i), counting(), (sum, n) -> sum * n)); System.out.println(result); // 10*4=40

24 Future of Java Beyond Java 12

25 Source: Project Amber Simplifying syntax (continuing)

26 JEP 305 Pattern Matching String formatted = "unknown"; if (obj instanceof Integer) { int i = (Integer) obj; formatted = String.format("int %d", i); } else if (obj instanceof Byte) { byte b = (Byte) obj; formatted = String.format("byte %d", b); } else if (obj instanceof Long) { long l = (Long) obj; formatted = String.format("long %d", l); } else if (obj instanceof Double) { double d = (Double) obj; formatted = String.format( double %f", d); } else if (obj instanceof String) { String s = (String) obj; formatted = String.format("String %s", s); }

27 JEP 305 Pattern Matching String formatted; switch (obj) { case Integer i: formatted = String.format("int %d", i); break; case Byte b: formatted = String.format("byte %d", b); break; case Long l: formatted = String.format("long %d", l); break; case Double d: formatted = String.format( double %f", d); break; case String s: formatted = String.format("String %s", s); break; default: formatted = obj.tostring(); }

28 Records public class Point { private final int x, y; public Point (int x, int y) { this.x=x; this.y=y; } public int hashcode() {... } public boolean equals(object obj) {... } public String tostring() {... } }

29 record Point (int x, int y) { } Records

30 Project Valhalla Value types and specialised generics Source:

31 Project Valhalla Goal: Reboot the layout of data in memory Source: Brian Goetz, Oracle Evolving the Java Language

32 Project Valhalla Motivation: Hardware has changed Multi-core The cost of cache misses has increased Source: Brian Goetz, Oracle Evolving the Java Language

33 Project Valhalla Motivation Source: Latency Numbers Every Programmer Should Know

34 Project Valhalla Motivation Source: Latency Numbers Every Programmer Should Know

35 Project Valhalla Value Object Value Object is an immutable type that is distinguishable only by the state of its properties

36 Project Valhalla Codes like a class, works like a primitive (Brian Goetz) Benefits: Reduced memory usage Reduced indirection Increased locality

37 Project Valhalla Value Types value class Point {long x, y ;}

38 Project Valhalla Value Types Can have method and field implement interfaces use encapsulation be generic Can t be mutated be sub-classed

39 Project Valhalla Generics over Values and Specialized Generics List<Long> points= new ArrayList<Long>(); List<Point> points= new ArrayList<Point>(); class Box<any T> { T value; } class Box<T=Long> class Box<T=Point> Source: John Rose:

40 Project Valhalla Current Status: Released public prototype LW1 VM support for value types (as subtypes of Object) Only language support for value types (no support for generics over values and specialized generics ) No support for migrating existing classes to value types yet Source: Brian Goetz, Oracle Evolving the Java Language

41 Project Metropolis Polyglot GraalVM for Java 8 (current version 1.0-RC13 as of ) Source:

42 Project Metropolis Goals: High performance for all languages Zero overhead interoperability between languages Language-level virtualization level for shared tooling Source: Oleg Selajev : Run Code in Any Language Anywhere with GraalVM

43 GraalVM Architecture Sources: Practical Partial Evaluation for High-Performance Dynamic Language Runtimes The LLVM Compiler Infrastructure

44 Project Sulong Source: Thomas Würthinger, Oracle : One VM to Rule Them All

45 GraalVM Architecture Sources: Practical Partial Evaluation for High-Performance Dynamic Language Runtimes The LLVM Compiler Infrastructure

46 SubstrateVM Source: Oleg Šelajev, Thomas Wuerthinger, Oracle: Deep dive into using GraalVM for Java and JavaScript

47 GraalVM and SubstrateVM Source: Oleg Selajev, Oracle : Run Code in Any Language Anywhere with GraalVM

48 Difference Between Substrate VM & JVM Models Source: Kevin Menard : Improving TruffleRuby s Startup Time with the SubstrateVM

49 GraalVM on SubstrateVM A game changer for Java & Serverless? Cold Start : Source: Ajay Nair Become a Serverless Black Belt

50 AWS Lambda cold start time by supported language Source: Yan Cui:

51 GraalVM on SubstrateVM A game changer for Java & Serverless? Java Function compiled into a native executable using GraalVM on SubstrateVM reduces cold start times memory footprint by order of magnitude compared to running on JVM.

52 Source: Project Loom Fibers and Continuations

53 Project Loom Motivation: Developers currently have 2 choices use blocking/synchronous API, which is simple, but less scalable (number of threads, that OS supports is far less that open and concurrent connections required) asynchronous API (Spring Project Reactor, RXJava 2), which is scalable, but complex, harder to debug and profile and limited (no asynchronous JDBC standard in this area) Source: Alan Bateman, Oracle Project Loom: Fibers and Continuations for Java

54 Project Loom Goals: explore and incubate Java VM features and APIs built on top of them for the implementation of lightweight user-mode threads (fibers), delimited continuations

55 Project Loom Continuation Continuation is a program object, representing a computation that may be suspended and resumed

56 Continuation package java.lang; public class Continuation { public Continuation (ContinuationScope scope, Runnable target) public final void run() public static void yield (ContinuationScope scope) } public boolean isdone()

57 Project Loom Continuations example () { var scope = new ContinuationScope( Example_Scope ); var continuation = new Continuation (scope, () -> { out.print( 1 ); Continuation.yield(scope); out.print( 2 ); Continuation.yield(scope); out.print( 3 ); Continuation.yield(scope); } }); while (! continuation.isdone()) { out.print( run.. ); continuation.run(); } Output: run.. 1 run.. 2 run.. 3

58 Project Loom Fibers Fibre is a lightweight thread scheduled not by the OS, but by the Java Runtime with low memory footprint and low taskswitching cost

59 Project Loom Fibers Strand (abstract thread) Fiber Thread Source: Talk Project Loom: Fibers and Continuations for the Java Virtual Machine by Ron Pressler

60 Project Loom Continuations Fiber = Continuation + Schedular

61 Project Loom Fibers java.lang.fibre currently supports: scheduling parking/unparking waiting for a fibre to terminate java.util.concurrent can park/unpark fibres Socket and Pipe APIs park fibers rather than block threads in syscalls Source: Alan Bateman, Oracle Project Loom: Fibers and Continuations for Java

62 Project Loom Current Status: Implemented initial prototype with Continuation and Fiber support Current prototype of Continuations and Fibers can run existing code (with some limitations) Current focus on Performance improvement Stable Fiber API Debugger support Source: Alan Bateman, Oracle Project Loom: Fibers and Continuations for Java

63 Project Loom Open Questions: Should the existing Thread API be completely re-examined? Can all existing code be run on top of Fibers? Source: Alan Bateman, Oracle Project Loom: Fibers and Continuations for Java

64 is still an interesting and great programming language

65 Questions?

66 Thank You!