Since moving to a 6 monthly release cadence, the Java platform is evolving more dynamically than ever before. It can be quite a challenge to stay on top of all the changes and new features. In this talk we're going to explore the most important developments in the Java API: which classes have been added, and what has been removed? Join Duke, the Java mascot, for a trip to space and learn which exciting new APIs provided by the Java platform can help him with his journey: The Java Vector API for utilizing the SIMD capabilities of modern CPU architectures The Foreign Linker API for integrating with native code The JFR Event Streaming API for publishing JDK Flight Recorder Events We'll also take a look at some useful changes to the Java runtime, such as CDS archives for a faster spaceship..., uhm, application launch!

1. To the Moon and Beyond
With Java 17 APIs!
Gunnar Morling
Software Engineer, Red Hat
@gunnarmorling

4. #Java17APIs @gunnarmorling
“Commit [ourselves] to
achieving the goal, before
this decade talk is out, of
landing a man Duke on the
Moon and returning him
safely to the Earth”
Today’s Mission
John F. Kennedy

5. The Vector API 1
JFR Event Streaming
2
3
The Foreign Linker
API

6. #Java17APIs @gunnarmorling
● Projects
○ Debezium
○ Quarkus
○ Hibernate
● MapStruct, JfrUnit, kcctl 🧸
● Java Champion
● @gunnarmorling
Gunnar Morling
Open Source Software Engineer at Red Hat

7. The Vector API
1

8. #Java17APIs @gunnarmorling
The Vector API
JEPs 338 / 414 / 417
java.util.Vector?!

9. #Java17APIs @gunnarmorling
“Introduce an API to express vector
computations that reliably compile at runtime
to optimal vector instructions on supported
CPU architectures, thus achieving
performance superior to equivalent scalar
computations.”
The Vector API
JEPs 338 / 414 / 417
JEP 417

10. #Java17APIs @gunnarmorling
The Vector API
Goals
Clear and concise API
1
Reliable runtime compilation
and performance on
x64 (SSE, AVX) and
AArch64 (NEON, SVE)
2
3 4
Platform agnostic
Graceful degradation

11. #Java17APIs @gunnarmorling
The Vector API
Use Cases
● Image, text, signal
processing
● Encryption
● Machine Learning
● etc.

12. #Java17APIs @gunnarmorling
The Vector API
Terminology

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The Vector API
Example – Scalar
c = -(a2
+ b2
)

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The Vector API
Example – Vector

15. #Java17APIs @gunnarmorling
The Vector API
Example – Vector

16. #Java17APIs @gunnarmorling
The Vector API
Example – Vector

17. #Java17APIs @gunnarmorling
The Vector API
Example – Vector

18. #Java17APIs @gunnarmorling
The Vector API
Example – Vector

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The Vector API
A Very Rich API

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The Vector API
Example – FizzBuzz

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The Vector API
FizzBuzz – Performance
Benchmark Mode Cnt Score Error Units
scalarFizzBuzz thrpt 5 2204774,792 ± 76581,374 ops/s
simdFizzBuzz thrpt 5 8830433,250 ± 69955,161 ops/s
MacBook Pro 2019 (2,6 GHz 6-Core Intel Core i7, 32GB RAM)

22. #Java17APIs @gunnarmorling
The Vector API
Examining Assembly Code with Hsdis

23. #Java17APIs @gunnarmorling
The Vector API
Examining Native Assembly
"conditionally copies
byte elements from
the source operand to
the destination
operand depending
on mask bits defined
in the implicit third
register argument"
felixcloutier.com

24. Detour
Identifying JDK API
Changes by Yourself

25. #Java17APIs @gunnarmorling
Detour: Identifying API Changes
javaalmanac.io

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Detour: Identifying API Changes
github.com/AdoptOpenJDK/jdk-api-diff

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Detour: Identifying API Changes
chriswhocodes.com/jepsearch.html

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Detour: Identifying API Changes
JavaDoc ab Version 17

29. 1
JFR Event Streaming 3
2
The Vector API
The Foreign Linker
API

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● Accessing native Memory (JEP 383)
● Accessing native APIs (JEP 389)
○ Moving specific parts to native code
○ Using existing native libraries
● Vector API
Projekt Panama
Integration of JVM and Native Code

31. #Java17APIs @gunnarmorling
Foreign Linker API
Using Method Handle

32. #Java17APIs @gunnarmorling
Foreign Linker API
Using Method Handle

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Foreign Linker API
Using Method Handle

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● Provide or create header file
● Generate binding (Panama EA build required)
Foreign Linker API
jextract

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Foreign Linker API
jextract

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Foreign Linker API
github.com/sundararajana/panama-jextract-samples

37. Detour
Removed APIs

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● RMI Activation
● Pack 200
● Nashorn JavaScript-Engine
● Deprecated for Removal in Java 17
○ Applet API
○ Security Manager
Detour: Removed APIs
Tackling the Maintenance Burden
→ 🤷
→ 🤷
→ Standalone Nashorn
(since Java 15), GraalJS

39. 1
JFR Event Streaming
2
3
The Vector API
The Foreign Linker
API

40. #Java17APIs @gunnarmorling
OpenJDK Flight Recorder
● “JVM framework for troubleshooting,
monitoring and profiling”
● 150+ built-in event types
● Support for custom events
● Open source since Java 11
● Meant for “Always on” usage in production

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JFR Event Types
https://bestsolution-at.github.io/jfr-doc/

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JFR Event Streaming
JEP 349
● Processing JFR events in “real-time”
● Use Cases
○ Export to monitoring services
○ Performance tests (JfrUnit)
○ Predictive analytics

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JFR Event Streaming
API

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JFR Event Streaming
Out-of-process: github.com/flight-recorder/health-report

45. #Java17APIs @gunnarmorling
● Performance tests based on metrics like latency/throughput
often unstable
● JfrUnit
○ Assertions based on proxy metrics
○ Plain JUnit-Tests
○ Analysis via JDK Mission Control
JFR Event Streaming
Use Case: Performance Regression Tests with JfrUnit
“Unit testing,
for performance”

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JFR Event Streaming
Asserting Socket IO with JfrUnit

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JFR Event Streaming
Asserting Socket IO with JfrUnit

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JFR Event Streaming
Asserting Socket IO with JfrUnit

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JFR Event Streaming
Asserting Socket IO with JfrUnit

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JFR Event Streaming
Asserting Socket IO with JfrUnit

51. Detour
AppCDS

52. #Java17APIs @gunnarmorling
JFR Event Streaming
Asserting Socket IO with JfrUnit

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● Class Data Sharing: Memory mapped class metadata
● Default CDS archive for JDK classes since Java 12 (JEP 341)
● AppCDS: CDS archive for your own classes
Detour: Faster Start-up with AppCDS
No Need to Go Native?

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Detour: AppCDS
Quarkus App – Time to First Response
Hetzner Cloud CX4 (4 vCPUs, 16GB RAM)

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Detour: AppCDS
Start-up Time of Apache Kafka

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Java 17 – An Update Well Worth It!
Many Improvements Across the Board...
Language
API
Runtime

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What We Didn’t Talk About...
New Language Features

59. #Java17APIs @gunnarmorling
● Shenandoah GC
● Improvements to native GraalVM binaries
○ JFR support
○ Debug symbols
● AArch64/Linux port; project Lilliput
● Persistent memory support (JEP 352, mashona.io)
● Supported OpenJDK distribution
Red Hat & OpenJDK
Past and Current Contributions

60. #Java17APIs @gunnarmorling
● JEP Search
https://chriswhocodes.com/jepsearch.html
● Blog (Vector API, JFR Event Streaming,
AppCDS, etc.)
https://www.morling.dev/
● JfrUnit
https://github.com/moditect/jfrunit
● Red Hat build of OpenJDK
https://developers.redhat.com/products/openjdk/overview
Resources

61. #Java17APIs @gunnarmorling
Q&A
gunnar@hibernate.org
@gunnarmorling
📧
Contact