Native Image Committer and Community Meeting 2023-09-21

[christianwimmer]

List of all past and upcoming meetings: #3933

New and Noteworthy

• GraalVM for JDK 21, i.e., GraalVM 23.1, is released.
  The next feature freeze for GraalVM 24.0 is on Dec. 7, aligned with the branch-off of JDK 22 for OpenJDK.

• Last minute decision was to not enable the new class initialization strategy in the GraalVM 23.1 release
  [GR-48529] Add '--strict-image-heap' option and use old class initialization by default to allow easier adoption. #7393
  [GR-48529] Fix the command argument in the clinit error msg. #7439

• We bumped the Java lanaguage level to 21, and removed all unnecessary code for pre-21 Java versions. For the forseeable future, we will keep Java 21 suppor tested on the master branch, so that Native Image always remains compatible with an LTS version of Java.
  [GR-43733] Change Java source level for native image to 21. #7379
  [GR-43733] Remove code for old JDK versions. #7389
  [GR-43733] Remove code for old JDK versions (part 2). #7399
  [GR-48372] Remove no longer needed JDK-specific JFR code. #7341

• The shadow heap is now used for all constant folding also during AOT compilation, and later on for image heap writing. This is a major step towards having a complete shadow heap and not relying on the hosted HotSpot heap after analysis. But for now, there is still a "verification" step of the shadow heap after AOT compilation to update some caches.
  [GR-42996] Redirect constant pool lookup through the shadow heap. #7436
  [GR-42996] Clean up use of ImageHeapConstant. #7460
  [GR-42996] [GR-46644] Cleanup shadow heap code. #7422
  [GR-42996] More heap scanning refactoring. #7388
  [GR-42996] Refactor shadow heap verification and fix lazy scanned values. #7376
  [GR-42996] Fix lazy scanned values. #7347
  [GR-42996] Refactor shadow heap. #7325

• Compatibility:
  [GR-47186] Unified native-image classloader for module- and class-path. #7302
  [GR-47449] Verify return types of substituted methods #7340

• Monitoring / tools:
  [GR-48343] [GR-48359] Add support for JFR events AllocationRequiringGC and SystemGC. #7463

Deep Dive: Module system support

• https://github.com/oracle/graal/blob/c45584bf7c704077429404fe4bef9e32b57e70a9/substratevm/docs/module-system/ModuleSystemSupportHosted.md
• https://github.com/oracle/graal/blob/c45584bf7c704077429404fe4bef9e32b57e70a9/substratevm/docs/module-system/ModuleSystemSupportRuntime.md