JDK 9, 10, 11 and Beyond

© Copyright Azul Systems 2018
@speakjava
JDK 9, 10, 11 and Beyond:
Delivering New Features in the JDK
Simon Ritter
Deputy CTO, Azul Systems
1

JDK 9: Big And Small Changes
2

Java Platform Module System (JPMS)
 The core Java libraries are now a set of modules (JEP 220)
– 75 OpenJDK modules: 27 Java SE, 48 JDK
– Oracle JDK: 14 additional JDK, 8 JavaFX, 2 Oracle specific
 Most internal APIs now encapsulated (JEP 260)
– sun.misc.Unsafe
– Some can be used with command line options
3

jlink: The Java Linker (JEP 282)
4
Modular run-time
image
…confbin
jlink
$ jlink --modulepath $JDKMODS
--addmods java.base –output myimage
$ myimage/bin/java –-list-modules
java.base@9
lib

jlink: The Java Linker (JEP 282)
$ jlink --module-path $JDKMODS:$MYMODS
--addmods com.azul.zapp –-output myimage
$ myimage/bin/java –-list-modules
java.base@9
java.logging@9
java.sql@9
java.xml@9
com.azul.zapp@1.0
com.azul.zoop@1.0
com.azul.zeta@1.0

Moving Java Forward Faster

Java Platform Development
 Development of releases takes time
– JDK 6: 2 years and 2 months after JDK 5
7

Migrating To A New Version
 Plenty of time to continue with previous release
– JDK 6: 2 years and 11 months of public JDK 5 updates
– JDK 7: 1 year and 9 months of public JDK 6 updates
– JDK 8: 1 year and 1 month of public JDK 7 updates
 Also allows for stabilisation of new platform before
migrating applications in production
8

The Java Platform Today
9
Stable
Secure
Free

OpenJDK: New Release Model
 A new version of the JDK will be released every six months
– March and September
– Started this year with JDK 10 and JDK 11
 OpenJDK development will be more agile
– Previous target was a release every two years
 Features will be included only when ready
– Targeted for a release when feature complete
10

Long Term Support Releases
 Long term support for all releases is not practical
– One Long Term Support (LTS) release every three years
 JDK 8 has been classified as an LTS release
 JDK 8 public updates stop in January 2019 for commercial users
 Non-commercial users get updates until December 2020
 Next LTS release is JDK 11
 JDK 9 and JDK 10 are feature releases
 Updates for only six months
11

Which JDK Binary
 Traditional Oracle branded binary (java.oracle.com)
– Oracle Binary Code License (FoU restrictions)
 New OpenJDK binary (jdk.java.net)
– GPLv2 with CPE license (no restrictions)
– Security and bug fix updates only for six months
 Only until next JDK release
 Two scheduled updates
– No overlap of updates for previous version
12

Converged Binaries
Oracle JDK
OpenJDK
Java SE
JDK 10 and earlier
Java SE
OpenJDK
& Oracle JDK
JDK 11 and later

Converged Binaries (JDK 11)
 Some closed-source parts of the JDK will be open-sourced
– Flight recorder
– Mission control ✔
– Others ✔
 Other closed-source parts will be removed
– Browser Plugin
– Java Web Start
– JavaFX
14

JDK 9 Onwards And Compatibility
15
"Clean applications that just depend on java.se
should just work" - Oracle

JDK 9: The Clean Up Starts
 JDK 9 was a significant change for Java
– Deprecated APIs were removed for the first time
 Six methods and one class
 JDK 10 removed 1 package, 6 classes, 9 methods and 1 field
– Redundant features eliminated
 jhat tool, JVM TI hprof agent
 Numerous deprecated GC options removed
– Significant command line changes
 JDK 9 removed 187 -XX flags
 JDK 10 removed 36 -XX flags
16

Housekeeping Will Continue
 More significant removals in JDK 11
– Applets, Browser Plugin, Web Start, JavaFX
– java.se.ee meta-module
 java.corba
 java.transaction
 java.activation
 java.xml.bind
 java.xml.ws
 java.xml.ws.annotation
 More in the future
– Nashorn deprecated, CMS garbage collector?
17

Compatibility Not Guaranteed
 New versions of Java may include breaking changes
– Anything for removal will be deprecated first
– Minimum of one release warning
 Could be only six months
18

Eliminating Confusion
 There will be an LTS release every three years
– This does NOT mean 3 years of free updates
 Oracle JDK (from JDK 11) can ONLY be used in production
with a commercial support contract
– The only free JDK 11 and later will be OpenJDK binaries
 To continue to receive free updates to the JDK you MUST
update your JDK EVERY SIX MONTHS
 JDK 8 can be used indefinitely for free
– But without any further security patches and bug fixes
19

New JDK Update Schedule

The Java Platform Soon
21
Stable
Secure
Free
Choose two out of three

JDK 10

Local Variable Type Inference
 JEP 286
– Simple use cases
– Style guidelines available
– Good (appropriate use of variable name)
– Poor
 Infered type is PriorityQueue<Object>
23
var list = new ArrayList<String>(); // infers ArrayList<String>
var stream = list.stream(); // infers Stream<String>
var stringList = List.of("a", "b", "c");
var itemQueue = new PriorityQueue<>();

JDK 10: JEPs
 JEP 307: Parallel Full GC for G1
– Still a full GC with potentially big pauses
 JEP 310: Application Class-Data Sharing
– Previous commercial Oracle feature
 JEP 317: Experimental Java-based JIT compiler (Graal)
 JEP 319: Root Certificates
– default set of root CA certificates
 JEP 296: Consolidate JDK forests into single repo
– Eight repos becomes one
24

JDK 10: JEPs
 JEP 316: Heap allocation on alternative devices (Intel)
– NV-RAM with same semantics as DRAM
 JEP 313: Remove javah tool
– Same functionality through javac
 JEP 304: Garbage Collector Interface (Red Hat)
– Easier to add new algorithms (JVM internal)
 JEP 312: Thread-Local Handshakes
– Execute callbacks on threads without performing a global
VM safepoint
25

JDK 10: APIs
 73 New APIs
– List, Set, Map.copyOf(Collection)
– Collectors
 toUnmodifiableList
 toUnmodifiableMap
 toUnmodifiableSet
– Optional.orElseThrow()
26

JDK 10: Miscellaneous
 XMLInputFactory.newFactory() de-deprecated
(precated?)
 com.sun.security.auth package
– Six deprecated classes removed
 java.lang.SecurityManager
– One deprecated field and seven methods removed
 JVM now more Docker container aware
– Uses container CPU count and memory size
– Namespace issues resolved (pids)
27

JDK 11

JDK 11
 17 JEPs
 3 from outside Oracle
– JEP 318: Epsilon garbage collector (Red Hat)
– JEP 315: Improve Aarch64 intrinsics (Red Hat)
– JEP 331: Low overhead heap profiling (Google)
29

JDK 11: JEPs
 JEP 309: Dynamic Class-file constants
– Like invokedynamic but for class-file constants
– Bootstrap method used at runtime, not compile time
– Useful for compiler and language developers
 JEP 328: Flight Recorder
– Final piece of aligning OpenJDK and Oracle JDK
30

JDK 11: JEPs
 JEP 320: Remove CORBA and Java EE modules
– The power of a module system
 JEP 321: HTTP client
– HTTP/2 support
– Incubating module from JDK 9 standardised
 JEP 323: Local variable syntax for Lambda parameters
– Extending JEP 286 in JDK 10
– (var x, var y) -> x.process(y)
31

JDK 11: JEPs
 JEP 324: Key Agreement with Curve25519 and Curve448
– More efficient and secure than existing ECDH
 JEP 327: Unicode 10
– 8,518 new characters (seriously)
– Bitcoin symbol, Nishu, Soyombo, Zanabazar Square
– Long awaited (?) Colbert emoji
32

JDK 11: New APIs
 New methods but no new classes
– InputStream nullInputStream()
– Writer nullWriter()
– Path of(String, String ...)
33

Longer Term JDK Futures

OpenJDK Projects
 Amber
– Simplifying syntax
 Valhalla
– Value types and specialised generics
 Loom
– Continuations and fibres
 Metropolis
– The JVM re-written in Java
 Panama
– FFI replacement for JNI
35

Project Amber
 JEP 286: Local variable type inference
– Delivered in JDK 10
 JEP 323: Local variable syntax for Lambdas
– Will be delivered in JDK 11
36

Project Amber
 JEP 302: Lambda leftovers
– Single underscore for unused parameters
 JEP 326: Raw string literals (JDK 12)
– Use single backquote
– `c:Userssimon`
– ```A string with a `` in it```
37

JEP 305: Pattern Matching
 Type test and switch statement support to start
38
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();
}

JEP 325: Switch Expressions (JDK 12)
39
int numLetters;
switch (day) {
case MONDAY:
case FRIDAY:
case SUNDAY:
numLetters = 6;
break;
case TUESDAY:
numLetters = 7;
break;
case THURSDAY:
case SATURDAY:
numLetters = 8;
break;
case WEDNESDAY:
numLetters = 9;
break;
default:
throw new IllegalStateException("Huh?: " + day); };

JEP 325: Switch Expressions
int numLetters = switch (day) {
case MONDAY, FRIDAY, SUNDAY -> 6;
case TUESDAY -> 7;
case THURSDAY, SATURDAY -> 8;
case WEDNESDAY -> 9;
default -> throw new IllegalStateException("Huh?: " + day);
};

Project Valhalla
 Java has:
– Primitives: for performance
– Objects: for encapsulation, polymorphism, inheritance, OO
 Problem is where we want to use primitives but can't
– ArrayList<int> won't work
– ArrayList<Integer> requires boxing and unboxing,
object creation, heap overhead, indirection reference
41

Project Valhalla
 Value types
 "Codes like a class, works like a primitive"
– Can have methods and fields
– Can implement interfaces
– Can use encapsulation
– Can be generic
– Can't be mutated
– Can't be sub-classed
42

Project Loom
 Further work on making concurrent programming simpler
– Threads are too heavyweight
 Loom will introduce fibres
– JVM level threads (remember green threads?)
– Add continuations to the JVM
– Use the ForkJoinPool scheduler
– Much lighter weight than threads
 Less memory
 Close to zero overhead for task switching
43

Project Metropolis
 Run Java on Java
– Rewrite most of the JVM in Java
 Use the Graal compiler project as significant input
 Easier ports to new platforms
– Less native code to modify and compile
 Faster new features on front-end
– Easier to write Java than C++
 Performance is an issue to be explored and resolved
– AOT compiler in JDK 9 is the start of this
44

Azul's Zulu Java

Zulu Java
 Azul’s free binary distribution of OpenJDK
– Passes all TCK tests
 JDK 6, 7, 8, 9,10 and 11 (EA) available
 Wider platform support:
– Intel 64-bit Windows, Mac, Linux
– Intel 32-bit Windows and Linux
– ARM 32 and 64-bit
– PowerPC
46
www.azul.com/downloads/zulu

Summary

Java Continues To Evolve
 Faster Java releases
– Feature release every 6 months
– Access to free updates is a consideration
 Lots of ideas to improve Java
– Value types, fibres, syntax improvements
 Zulu Java has wide platform and JDK version support
– Very reasonable cost for commercial support
48

@speakjava
Thank You!
Simon Ritter
Deputy CTO, Azul Systems
49

JDK 9, 10, 11 and Beyond

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