Summary of JDK10 and What will come into JDK11 so far

1. Summary of JDK10
and
What will come into JDK11
Nameless Java Seminars at Fukuoka
2018/5/29 Naoki Kishida

2. About me
• Naoki Kishida
• LINE Fukuoka
• @kis

3. Agenda
• New Release Model
• About JDK 10
• About JDK 11
• About Java Support

4. New Release Model

5. 6-monthly release
• Oracle had announced they will
release Java every 6 months at
2017/9/6

6. Java new release cycle.
• Feature release every 6 months
– March and September(春分の⽇/秋分の⽇)
• Maintenance release every 3 months
– April and July for March release
– October and January for September release
• Long Term Support every 3 years
– The first LTS is for JDK 11
• Oracle JDK will be for only Oracle
customer
– Use OpenJDK instead.

7. Version number
• 2018/03 Feature release JDK10
• 2018/04 Maintenance release JDK10.0.1
• 2018/07 Maintenance release JDK10.0.2
• 2018/09 Feature release JDK11 LTS
• 2018/10 Maintenance release JDK11.0.1
LTS
• 2019/01 Maintenance release JDK11.0.2
LTS

8. Java SE 8 support is extended
• Oracle has extended Java SE 8
support at least until 2019/1
• It is available for the personal use
until 2020/12
• Java SE 8 support will finish after 3
months of JDK 11 release.
• We should move to JDK 11 by 2019/1
http://www.oracle.com/technetwork/jp/java/eol-135779-ja.html

9. Desktop technology
• Applet and Web Start is no longer
supported after JDK 11
• JavaFX will not be bundled with JDK11
– So far OpenJDK had not bundled JavaFX
• AWT and Swing will be supported
– There are many commits for JDK 11

10. About JDK 10

11. Java 10 JEPs
• 286 Local-Variable Type Inference
• 296 Consolidate the Repository
• 304 GC Interface
• 307 Parallel Full GC for G1
• 310 Application Class-Data Sharing
• 312 Thread-Local Handshakes
• 313 Remove the Native-Header Generation Tool(javah)
• 314 Additional Unicode Language-Tag Extensions
• 316 Heap Allocation on Alternative Momory Devices
• 317 Experimental Java-Based JIT Compiler
• 319 Root Certificates
• 322 Time-Based Release Versioning

12. 286: Local-Variable Type
Inferences
• var list = new ArrayList<String>()
• `var` is not a keyword
– but a special type
• We can use `var` as a variable name
• We can use `var` as a method name
• We can not use `var` as a class name

13. Where can we use `var`?
• OK
– Right Oprand has the type
• var strs = new ArrayList<String>();
• var path = Path.of(“http://example.com”);
• Should not
– Enclosing type
• ex: Supplier<String>, Optional<String>
ListenableFuture<String>
• var name = findName(id);
print(name.get()); // How should we care?

14. Another usage for `var`
• Anonymous class become useful
– ex: defining a local method
• var m = new Object() {
int twice(int x) {
return x * 2;
}
};
print(m.twice(3));

15. 304: Garbage-Collector
Interface
• GC is modularized.
• There are many GCs that will come.
– Epsilon GC
– ZGC
– Shenandoah
• Not to control GC by user code

16. 317: Experimental Java-Based
JIT Compiler
• Project Metoropolis
– java-on-java
• We can write JVM even with Scala?
– There is a possibility.

17. 307: Parallel Full GC for G1
• G1GC had been the default GC on JDK
9
• Full GC for G1 was not parallel.
• Until JDK 8, Parallel GC was the
default
• To smooth migration, Full GC for
G1GC also parallelize.
• But full GC should not occur.
– Ideally, it has no effect for us.

18. 310: Application Class-Data
Sharing
• CDS for system class is introduced in
JDK 5
• Share class data between multiple
JVM
on the same machine
– startup performance
– reduce the resource footprint
• JDK 10 allow to use CDS for
application class

19. 312: Thread-Local Handshakes
• JVM can stop an individual thread
– stop not just all thread

20. 313: Remove the Native-Header
Generation Tool(javah)
• javah is removed
• use `javac –h` instead

21. 314: Additional Unicode
Language-Tag Extensions
• Enhance java.util.Locale
• additional Unicode extensions
of BCP 47 language tag
– currency type
– the first day of the week
– region override
– time zone

22. 316: Heap Allocation on
Alternative Memory Devices
• Now we can use non-volatile RAM(不
揮発性メモリ) such as 3D XPoint
• This will enable the JVM to use
different types of memory system

23. 319: Root Certificates
• OpenJDK doesnʼt have Root
Certificates so far
• Oracle JDK have had it.
• To smooth migration, OpenJDK have
had it.

24. API Changes
• java.io.Reader
– long transferTo(Writer)
• java.lang.mainagement.RuntimeMXBe
an
– long getPid()
• java.util.List/Map/Set
– copyOf(Collection)
• java.util.stream.Collectors
– toUnmodifiableList/Set/Map

25. Docker aware
• Until JDK 9, JVM use the platform CPU
count/Memory size even if it is running
on Docker.
• JDK 10, JVM can use Docker setting for
CPU count/ Memory size if it is running
on Docker.
• VM Options
– -XX:InitialRAMPercentage
– -XX:MaxRAMPercentage
– -XX:MinRAMPercentage

26. Other Changes
• Kerberos configuration file krb5.conf
include *.conf in INCLUDEDIR
• -d32 and –d64 has been removed
• new JavaDoc tag. {@summary}
• policytool has been removed
• XMLInputFactory.newFactory() has
been “de-deprecated”
– it had been deprecated by mistake.

27. About JDK 11

28. Java 11 JEPs
• 309 Dynamic Class-File Constants
• 318 Epsilon: A No-Op Garbage Collector
• 320 Remove the Java EE and CORBA Modules
• 321 HTTP Client(Standard)
• 323 Local-Variable Syntax for Lambda Parameters
• 324 Key Agreement with Curve25519 and Curve448
• 327 Unicode 10
• 328 Flight Recorder
• 329 ChaCha20 and Poly1305 Cryptographic Algorithms
• 330 Launch Single-File Source-Code Programs

29. Expected JEPs for JDK11
• 326 Raw String Literals
• 325 Switch Expressions
• 181 Nest-Based Access Control

30. Launch Single-File Source-Code
Programs
• java Hello.java
– The file name does not need to be related
with the class name
• Shebang
– #! /usr/bin/java –source 10
– chmod +x hello
– ./hello

31. Raw String Literals
• var sql = ```select NAME
from MEMBER
where id=1```
• var regexp = ```hello¥¥n```
// same as “hello¥¥¥¥n”
• How to address indent

32. Switch Expressions
• Now `switch` is a statement
• int i;
switch (s) {
case “start”:
case “begin”:
i = 0;
break;
case “end”:
i = 1;
break;
default:
i = 2;

33. Switch Expressions
• int i = switch (s) {
case “start”,“begin”-> 0;
case “end” -> 1;
default -> 2;
}

34. Local-Variable Syntax for
Lambda Parameters
• list.map(s -> s.toUpperCase())
.collect(toList())
• list.map((var s) -> s.toUpperCase())
.collect(toList())
• list.map((@Nullable var s)
-> s.toUpperCase())
.collect(toList())

35. HTTP Client(Standard)
• Graduate the incubator
• var client HttpClient.newHttpClient();
var url = URI.create(url);
var req = HttpRequest.newBuilder(uri).build();
HttpResponse<String> res = client.send(
req, HttpResponse.BodyHandlers.ofString(
Charset.forName(“utf-8”));
return res.body();

36. Epsilon: A No-Op Garbage
Collector
• Do nothing!
• For evaluate the performance of
another feature
– GC will make a noise

37. Remove the Java EE and
CORBA Modules
• No one uses CORBA!
• The size is large
• Removing them, JDK will be smaller

38. Flight Recorder
• Logging the performance
• Now it is an open source
• Caution
– for before JDK10 is still commercial

39. Unicode 10
• Support Unicode 9 and Unicode 10

40. Dynamic Class-File Constants
• Use invokeDynamic for constant initialization

41. Key Agreement with
Curve25519 and Curve440
• RFC 7748
• More efficient and secure than ECDH

42. ChaCha20 and Poly1305
Cryptographic Algorithms
• RFC 7539
• Stream cypher
• Not support for TLS
• The first step of supporting in TLS

43. Nestmate
• To address inner class accessibility
• class Outer {
private int a;
class Inner {
void foo() { print(a); }
}
}
-> Outer & Outer$Inner
• Need to access the private member
• from Valhalla!

44. How to access
the nestmateʼs private now
• class Outer {
private int a;
int access$000() { return a;}
}
class Outer$Inner{
Outer outer;
void foo() { print(outer.access$000()); }
}
• It make some problem for the
Specialization in the Vallhala project

45. How to address
• Add 2 attribute for the class file format
– NestHost
– NestMembers

46. API changes in JDK11
• String::repeat/lines/strip...
• Predicate::not
• Optional::isEmpty
• Character::toString(int)
• Files
• ArrayIndexOutOfBoundsException
– the message is changed

47. String
• repeat
• isBlank
• lines
• strip/stripLeading/stripTrailing

48. Predicate::not
• lines.filter(s -> !s.isEmpty())
→
lines.filter(
Predicate.not(String::isEmpty))

49. Optional::isEmpty
• Optional has `isEmpty()`

50. Character::toString(int)
• We can write `Character.toString(65)`

51. Files
• String Files.read(Path)
• Path FIles.write(Path, String)
• Files.isSameContent(Path, Path)

52. ArrayIndexOutOfBoundsException
• jshell> new int[]{}[0]
| java.lang.ArrayIndexOutOfBoundsException thrown: 0
| at (#1:1)
->
jshell> new int[]{}[0]
| Exception java.lang.ArrayIndexOutOfBoundsException:
Index 0 out of bounds for length 0
| at (#8:1)

53. How about Stream#toList？
• modifiable? unmodifiable?
• What order?
• “it nulls a property of the Stream API
we have take time to keep.
The whole Stream API doesn't
depends on the Collection API”

54. About Java Support

55. Oracle JDK
• Same as the current support
• Very expensive for web servicer
• 100 servers on AWS -> 1おくえん

56. OpenJDK
• Official publishment says it has only 6
months support for each JDK release.
No LTS
• Mark Reinhold said OpenJDK will have
LTS
– but not on the web site yet
– LTS support is for 3 years. No overlap.

57. AdoptOpenJDK
• Project by London JUG
• IBM suponsored
• Provide pre-build JDK
• LTS support for 4 years

58. Zulu
• Provided by Azul System
• Free to download and use
• Enterprise support
– 100 servers $28,750/year
– unlimited servers $258,750/year

59. Support the new era
after Heisei
• Start to support the new era as
NewEra
• JDK12 will release 2019/3
• The new era will release early 2019/4
• JDK maintenance release will be late
2019/4
– JDK 12.0.1
• The new era will start 2019/5

60. Summary
• がんばろ