Native Image Committer and Community Meeting 2024-01-11

[christianwimmer]

List of all past and upcoming meetings: #3933

New and Noteworthy

• Release branches for GraalVM for JDK 22 (= GraalVM 24.0) are created. Bugfixes can still be merged. The master branch is now using JDK 23 promoted builds:
  [GR-50932] Update JVMCI to 23+4-jvmci-b01. #8120

• Improve performance of hashCode/equals/toString methods for records: The method handle intrinsification needed some "final tweak" to inline through the method handles for those methods. The plan is to merge this into GraalVM for JDK 22, and later backport also to GraalVM for JDK 21.
  [GR-51002] Improve intrinsification of method handles. #8109

• Proper exception for missing configuration elements:
  [GR-50259] Throw exceptions for missing resource bundle registrations #8059

• Several platforms are moving to pages sizes larger than 4 KByte. The "build time page size" is the maximum that the page size can be at run time, but it is allowed to be smaller at run time. So we are considering switching the default to 64 KByte.
  [GR-51078] Use 64k page size by default at image build-time. #8131

• Better diagnostics for Truffle languages that have too many methods reachable due to missing @TruffleBoundary or transferToInterpreter:
  [GR-50840] Cleanup Truffle Runtime Compilation and Improve Error Messages. #8032
  [GR-50840] Try to use calltree for call traces. #8082

• Shadow heap:
  [GR-50962] Add object reachability hooks. #8041 Avoid over-registration of reflective elements that end up to not be reachable.
  [GR-49410] Do not mark AnalysisType reachable when creating AnalysisField. #8011

• Usability:
  [GR-51074] Introduce ReportFatalErrorOnOutOfMemoryError #8091
  [GR-45281] Preprocess _MSC_FULL_VER to detect cl.exe version info. #8058

• Performance:
  [GR-51205] Avoid needlessly rescanning black objects. #8126

• Layered native images:
  [GR-49383] Implement base layer open-world analysis #8122
  [GR-49708] Separate DynamicHub from HybridLayout. #8070

• Cleanups:
  [GR-50773] Improve typing of GraphProvider and signatures. #7982
  [GR-48002] Remove non-chunked image heap and remove null regions that are part of the image. #8068

• Compatibility
  [GR-50975] Execute LogManager shutdown hook after all other shutdown hooks. #8069 standard output/input streams can be closed by user code, then native image low-level logging fails too. This is a workaround until we have a proper fix.

• Monitoring / tools:
  [GR-51007] JFR cleanups. #8057
  [GR-50985] Set alignment to 1 for Java DWARF debug info sections #8046
  We are working on improved Windows stack unwinding support, so that all native tools (profilers, debuggers) can always unwind the stack.

Deep Dive: Build libgraal with a different "runtime" compiler version than what is used by the native image generator

Currently, building libgraal (a native image of the Graal compiler that is then loaded by the Java HotSpot VM) can only put the same compiler into the native image that is also used to create the native image. For more flexible workflows, e.g., when integrating libgraal into a JDK that is "too new" to run native-image, it is desirable to decouple the compiler versions. This requires a clean class loader separation of the two compiler versions.

We will talk a bit about the motivation for this project, and show the current state of implementation (which is still far away from a pull request).