Native Image Committer Community Meeting 2022-06-30

[christianwimmer]

List of all past and upcoming meetings: #3933

New and Noteworthy

• Compatibility improvements
  We started working on JDK 19 support. Plan is to have a JDK 19 based release with full Project Loom support for the 22.3 release.
  [GR-39406] Add new class initialization strategy that allows all classes to be used at image build time. #4684 Please try it out and provide feedback
  [GR-38909] Move annotations for substitution system to the SDK module. #4683
  [GR-38011] Parse annotations without intializing them. #4614

• Module system support
  [GR-37582] Default to running image-builder on module path. #4468
  [GR-39171] Remove unqualified export of org.graalvm.nativeimage.impl packages. #4658

• Image size improvements
  [GR-18799] Share JNI wrapper methods between callees with the same signature. #4686

• Other
  b781892 The reachability analysis is a PhD research project and not ready yet for any production use.
  [GR-39497] Add support for JSON build output to GraalVM Native Image. #4685
  b2a17ab Remove old build output
  006c61d Introduce native-image driver command-line only options

• JFR / Heap dumps / Debugging
  Add support for JFR monitor enter events #4651
  [GR-38965] Support heap dumps in GraalVM CE Native Image. #4622
  [GR-38951] Introduce -XX:+DumpHeapAndExit option. #4612
  [GR-34179] Upgrade CE debug info feature to provide information about Java types for Windows/PECOFF #3732
  gdb-JDWP bridge: https://quarkus.io/blog/nativejdb-debugger-for-native-images/

Deep Dive

Parse annotations without initializing them

#4614 changes how annotations are processed in the native image generator. Instead of relying on the JDK to provide annotation objects, there is now a copy of the annotation data parser in the native image generator. With one crucial difference: when asking for an annotation of a specific class, not all annotations are instantiated. This is necessary to avoid initialization of all annotation classes at image build time.

Example of a bug solved by this: #4489

The new rules:

• No code in the image generator must use getAnnotation methods from the JDK, i.e., call it on Class/Method/Constructor/Field
• No code in the image generator must use getAnnotations, i.e., ask for all annotations of an element

Allow all classes to be used at image build time

#4684 - see the PR for a detailed description

Possible deep dive topics for next meeting

Please send suggestions, or "upvote" a suggestion, by adding a comment to this discussion.

• How to write "AOT friendly" Java code