SpringOne Platform 2017 Simon Ritter, Azul Systems "Following on from the popular “55 New Features in Java SE 8” we bring you the eagerly-awaited sequel, “55 New Features in JDK 9”. Obviously, the big new feature in JDK 9 is modularity and project Jigsaw, but there’s lots more to tempt developers. We’ll divide things into five categories: Features Standards Inside the JVM Specialised Housekeeping Join us on a whirlwind tour of what’s in (and what’s out) in JDK 9 so you’re ready to get started with the latest version of the most popular programming platform on the planet."

1. 55 New Features in JDK 9
Simon Ritter, Deputy CTO, Azul Systems
@speakjava
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2. © Copyright Azul Systems 2017
Major Features

3. © Copyright Azul Systems 2017
Modularity/Jigsaw
 Standard class libraries modularised (JEP 220)
– JDK now 94 modules (Java SE is 36)
 Most internal APIs now encapsulated (JEP 260)
– sun.misc.Unsafe
– Some can be used with command line options
 --add-exports
 --add-opens
 Modular source code (JEP 201)
– JDK source code re-organised to support modules
– Not the module system
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4. © Copyright Azul Systems 2017
Modularity/Jigsaw
 Compatability is an issue
– Mostly for libraries and frameworks
– Which most people use
– Override encapsulation of private APIs
 Leave everything on classpath to start with
 “Big kill switch” now has options
– Turns off encapsulation completely by default
– --illegal-access={permit,warn,debug,deny}
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5. © Copyright Azul Systems 2017
jlink: The Java Linker (JEP 282)
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Modular run-time
image
…confbin
jlink
$ jlink --modulepath $JDKMODS
--addmods java.base –output myimage
$ myimage/bin/java –-list-modules
java.base@9
jmods

6. © Copyright Azul Systems 2017
jlink: The Java Linker (JEP 282)
$ jlink --module-path $JDKMODS:$MYMODS
--addmods com.azul.app –-output myimage
$ myimage/bin/java –-list-modules
java.base@9
java.logging@9
java.sql@9
java.xml@9
com.azul.app@1.0
com.azul.zoop@1.0
com.azul.zeta@1.0
Version numbering for
information purposes only
“It is not a goal of the module
system to solve the version-
selection problem”

7. © Copyright Azul Systems 2017
Factory Methods For Collections (JEP 269)
 Static factory methods on List, Set and Map interfaces
– Create compact, immutable instances
– 0 to 10 element overloaded versions
– Plus varargs version for arbitary number of elements
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Set<String> set = new HashSet<>();
set.add("a");
set.add("b");
set.add("c");
set = Collections.unmodifiableSet(set);
Set<String> set = Set.of("a", "b", "c");

8. © Copyright Azul Systems 2017
Stream Enhancements
 dropWhile()/takeWhile()
– Like skip/limit but uses Predicate rather than number
 Improved iterate
– Enables a stream to be more like a for loop
 Parallel Files.lines()
– Memory mapped, divided on line break boundary
 Stream from Optional
– Stream of zero or one element
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9. © Copyright Azul Systems 2017
Multi-Release Jar Files (JEP 238)
 Multiple Java release-specific class files in a single archive
 Enhance jar tool to create multi-release files
 Support multi-release jar files in the JRE
– Classloaders
– JarFile API
 Enhance other tools
– javac, javap, jdeps, etc.
 Also, modular jar files
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10. © Copyright Azul Systems 2017
REPL: jshell (JEP 222)
 Read-Eval-Print Loop
– Simple prototyping
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11. © Copyright Azul Systems 2017
Concurrency Updates (JEP 266)
 Reactive streams publish-subscribe framework
 Asynchronous, non-blocking
 Flow
– Publisher, Subscriber, Processor, Subscription
 SubmissionPublisher utility class
– Asynchronously issues items to current subscribers
– Implements Flow.Processor
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12. © Copyright Azul Systems 2017
Concurrency Updates (JEP 266)
 CompletableFuture additions
– Delays and timeouts
– Better support for sub-classing
– New static utility methods
 minimalCompletionStage
 failedStage
 newIncompleteFuture
 failedFuture
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13. © Copyright Azul Systems 2017
Enhanced Deprecation (JEP 277)
 We have @deprecated and @Deprecated
– Used to cover too many situations
 New methods in Deprecated annotation
– boolean forRemoval()
 Will this ever be removed?
– String since()
 JDK Version when this was deprecated
 Several @Deprecated tags added
– java.awt.Component.{show(),hide()} removed
 jdeprscan command to produce report
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14. © Copyright Azul Systems 2017
Milling Project Coin (JEP 213)
 Single underscore no longer valid as identifier
– Ready for use in Lambdas
 Private methods in interfaces
– Multiple inheritance of behaviour makes this logical
 Effectively final variables in try-with-resources
– Variables from outside try block
 Allow @SafeVarargs on private instance methods
– In addition to constructors, final and static methods
 Diamond operator with anonymous classes
– Extending type inference further
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15. © Copyright Azul Systems 2017
Standards

16. © Copyright Azul Systems 2017
Updating To Relevant Standards
 Unicode 7.0/8.0 (JEP 227/267)
– 7.0: 2,834 new characters
– 8.0: 7,716 new characters
 PKCS12 key stores by default (JEP 229)
– Move from JKS to PKCS12
 HTML5 javadocs (JEP 224)
– Flashier documentation
 SHA 3 hash algorithms (JEP 287)
– Keeping ahead of the hackers
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}seriously!

17. © Copyright Azul Systems 2017
Smaller Features
 UTF-8 property files (JEP 226)
– ResourceBundle API updated to load these files
 DRBG-Based SecureRandom implementations (JEP 273)
– Deterministic Random Bit Generator
 XML Catalog API (JEP 268)
– Supports OASIS XML catalog API v1.1
– For use with JAXP
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18. © Copyright Azul Systems 2017
Inside The JVM

19. © Copyright Azul Systems 2017
Default Collector: G1 (JEP 248)
 G1 now mature in development
 Designed as low-pause collector
 Concurrent class unloading (JEP 156) JDK8u40
– Useful enhancement to improve G1
 Still falls back to full compacting collection
– Pause times proportional to heap size
– Use Zing from Azul for truly pauseless
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20. © Copyright Azul Systems 2017
Better String Performance
 Compact strings (JEP 254)
– Improve the space efficiency of the String class
– Not using alternative encodings
 Store interned strings in CDS archive (JEP 250)
– Share String and char[] objects between JVMs
 Indify String concatenation (JEP 280)
– Change from static String-concatenation bytecode
sequence to invokedynamic
– Allow future performance improvements
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21. © Copyright Azul Systems 2017
Marlin Graphics Renderer (JEP 265)
 Replaces Pisces open-source renderer
– Comparable performance to closed-source Ductus
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22. © Copyright Azul Systems 2017
Smaller Features
 Improve contended locking (JEP 143)
– Field reordering/cache line alignment
 Leverage CPU instructions for GHASH and RSA (JEP 246)
– Up to 150x better performance (for specific tests)
 Update JavaFX to newer version of GStreamer (JEP 257)
– Media class
– Better security, stability and performance
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23. © Copyright Azul Systems 2017
Smaller Features
 Segmented Code Cache (JEP 197)
– Separate non-method, profiled and non-profiled code
 Unified JVM logging (JEP 158)
– Common logging system for all components of JVM
 Unified GC logging (JEP 271)
– Re-implement GC logging using unified JVM logging
– Many command line options changed
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24. © Copyright Azul Systems 2017
Specialised

25. © Copyright Azul Systems 2017
Spin-Wait Hints (JEP 285)
 Proposed by Azul
– We rock!
 A new method for Thread class
– onSpinWait()
 Enables the x86 PAUSE instruction to be used from Java
code
– If available
– Ignored otherwise
– Improved performance for things like Disruptor
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26. © Copyright Azul Systems 2017
Variable Handles (JEP 193)
 Replacement for parts of sun.misc.Unsafe
 Fence operations
– Fine grained memory control
– Atomic operations on object fields and array elements
 VarHandle
– compareAndExchange(), compareAndSet()
– getAndAdd(), getAndSet()
– acquireFence(), releaseFence()
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27. © Copyright Azul Systems 2017
AOT Compilation (JEP 295)
 Experimental feature in JDK 9
– -XX:+UnlockExperimentalVMOptions
– Only the java.base module has AOT version
 jaotc command
– jaotc --output libMyStuff.so MyStuff.jar
 JVM uses AOT code to replace interpreted
– Can recompile with C1 to collect further profiling data
– Recompile with C2 for optimum performance
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28. © Copyright Azul Systems 2017
Smaller Features
 Compiler control (JEP 165)
– Control of C1/C2 JIT, not javac
– Directive file
– Runtime changes via jcmd
 Process API updates (JEP 102)
– Native process (Process/ProcessHandle)
– More information: pid, arguments, start time, CPU usage,
name
– Control subject to security manager permissions
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29. © Copyright Azul Systems 2017
Housekeeping

30. © Copyright Azul Systems 2017
New Version String Format (JEP 223)
 Old
– Limited update release/Critical patch update (CPU)
– Download: Java SE 8u131, java -version: jdk1.8.0_131
– Which has more patches, JDK 7u55 or JDK 7u60?
 New
– JDK $MAJOR.$MINOR.$SECURITY.$PATCH
– Easy to understand by humans and apps
– Semantic versioning
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31. © Copyright Azul Systems 2017
New Version String Format (JEP 223)
 Old
– Limited update release/Critical patch update (CPU)
– Download: Java SE 8u131, java -version: jdk1.8.0_131
– Which has more patches, JDK 7u55 or JDK 7u60?
 New, new
– JDK $YEAR.$MONTH
– New 6 month release cadence, Mar/Sep
– Next version would be JDK 18.3, then 18.9
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32. © Copyright Azul Systems 2017
JDK Version Numbering
 New, new scheme. Just proposed JEP 322
– $FEATURE.$INTERIM.$UPDATE.$PATCH
– FEATURE: Was MAJOR, i.e. 10, 11, etc.
– INTERIM: Was MINOR. Always zero, reserved for future use
– UPDATE: Was SECURITY, but with different incrementing rule
– PATCH: Emergency update outside planned schedule
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33. © Copyright Azul Systems 2017
JDK/JRE File Structure (JEP 220)
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bin
Pre-JDK 9 JDK 9
lib
tools.jar
jre
bin
rt.jar
lib
libconfbin
jre directory
tools.jar
rt.jar
jmods

34. © Copyright Azul Systems 2017
Smaller Features
 Searchable API documentation (JEP 225)
– Finally! Java API docs enter the 21st century
 Annotations pipeline 2.0 (JEP 217)
– Repeating, type and Lambda annotations in JDK 8
– Redesign of javac annotation pipeline
 Parser API for Nashorn (JEP 236)
– API for Nashorn abstract tree syntax
– Nashorn implements ECMAScript 5.1 spec.
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35. © Copyright Azul Systems 2017
General Clean Up
 Disable SHA-1 certificates (JEP 288)
– Mostly
 In some situations SHA-1 certs. will still be accepted
 Deprecate the Applet API (JEP 289)
– Not many people still use this
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36. © Copyright Azul Systems 2017
Removed From JDK 9
 Six deprecated APIs (JEP 162)
– {Add,Remove}ActionListener
– Pack200, Unpack200 and LogManager
 com.sun.security.auth.callback.DialogCallbackHandle
r
– Part of JAAS
 JRE version selection command line option (JEP 231)
– -version:release no longer accepted
– -version still works
 Demos and samples (JEP 298)
– Out-of-date, unmaintained 36

37. © Copyright Azul Systems 2017
Removed From JDK 9
 JVM TI hprof agent (JEP 240)
– Only ever intended as a demo of JVM TI
– Useful features now in other tools (like jmap)
 Remove the jhat tool (JEP 241)
– Experimental tool added in JDK 6
– Unsupported
– Better heap visualisation tools available
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38. © Copyright Azul Systems 2017
Removed GC Options (JEP 214)
 Deprecated in JDK 8 (JEP 173)
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DefNew + CMS : -XX:-UseParNewGC -XX:+UseConcMarkSweepGC
ParNew + SerialOld : -XX:+UseParNewGC
ParNew + iCMS : -Xincgc
ParNew + iCMS : -XX:+CMSIncrementalMode -XX:+UseConcMarkSweepGC
DefNew + iCMS : -XX:+CMSIncrementalMode -XX:+UseConcMarkSweepGC
-XX:-UseParNewGC
CMS foreground : -XX:+UseCMSCompactAtFullCollection
CMS foreground : -XX:+CMSFullGCsBeforeCompaction
CMS foreground : -XX:+UseCMSCollectionPassing

39. © Copyright Azul Systems 2017
What Next?

40. © Copyright Azul Systems 2017
OpenJDK: New Release Model
 A new version of the JDK will be released every six months
– March and September
– Starting next year
 OpenJDK development will be more agile
– Previous target was a release every two years
 Three and a half years between JDK 8 and JDK 9
 Features will be included only when ready
– Targeted for a release when feature complete
– Not targeted at specific release when started
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41. © Copyright Azul Systems 2017
Availability Of JDK Updates
 Oracle is switching to a long term support (LTS) model
 LTS release will have 3 years of public updates
– JDK 8 has been classified as an LTS release
 It will have updates for more than 3 years
– Next LTS release will be September, 2018
 Non-LTS releases are "Feature Releases"
– JDK 9 is a feature release
– Public updates only until next feature release
 JDK 9 public updates end in March, 2018
 No overlap of support
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42. © Copyright Azul Systems 2017
JDK 10
 JSR 383 submitted and expert group formed
– Lead by Brian Goetz
– Oracle, IBM, Red Hat, SAP and Azul (Me)
 Schedule approved
– Development complete: 14/12/17
– Release candidate: 22/2/18
– General Availability: 20/3/18
 Early draft review already published
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43. © Copyright Azul Systems 2017
JDK 10
 Several JEPs proposed to target
– 304: GC interface
– 307: Fully parallel G1
– 310: Application class-data sharing
– 316: Heap allocation on alternative devices
 JEP 286: Local variable type inference
var list = new ArrayList<String>(); // infers ArrayList<String>
var stream = list.stream(); // infers Stream<String>
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44. © Copyright Azul Systems 2017
JDK 11
 JSR 384 recently submitted to JCP
 Expert group being formed
– Likely to be the same as JSR 383 (and JSR 379)
 More of a rolling JSR
 JEPs proposed so far
– 318: Epsilon GC
– 309: Dynamic class file constants
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45. © Copyright Azul Systems 2017
Summary

46. © Copyright Azul Systems 2017
Zulu Java
 Azul’s binary distribution of OpenJDK
– Passes all TCK tests
– Multi-platform (Windows, Linux, Mac)
– FREE!
 Happy to sell you support, including older versions
 JDK 6, 7, 8 and 9
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www.zulu.org/download

47. © Copyright Azul Systems 2017
JDK 9
 Big new feature is modularity
– Covers numerous different areas
– Modules, jink, etc.
 Smaller developer features
– New APIs for streams
– Reactive API
– REPL/jshell
 Many smaller performance/standards features
 Test with JDK 9, consider deployment options
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