Native Image Committer and Community Meeting 2024-02-08

[christianwimmer]

List of all past and upcoming meetings: #3933

New and Noteworthy

• Bugfixes for GraalVM 24.0 can still be merged, but we are certainly ramping down and merge fewer PRs.

• Proposal for locale handling: Provide an API option to include resource bundles for certain locales, and set the default locale at run time when the native image starts.
  [GR-52096] Determine the locale of Native Image executables at run-time #8295

• Special exceptions for missing configuration: The changes in the configuration file formats will need to be backported to GraalVM for JDK 21 and 17, so that configuration files (especially in the metadata repository) work across all GraalVM versions.
  [GR-50259] Throw exceptions for missing resource bundle registrations #8059
  Use glob patterns in resource configuration files
  [GR-50432] Allow fields to be registered for reflection without being made reachable #8271

• New class initialization policy: When registering a class (not a package) for initialization at image build time, the class is initialized immediately (like it was the case with the old class initialziation policy). This is useful to break class initialization cycles and avoid deadlocks at image build time.
  [GR-51416] Registering a class as initialize-at-build-time should immediately trigger initialization. #8193
  [GR-51384] Break class initialization cycle in XML classes. #8256

• Usability:
  [GR-51078] Use 64k page size by default at image build-time. #8131
  [GR-49996] Make -jar only implicitly set image name if not already defined previously. #8220
  [GR-51104] Catch disallowed objects in object reachable callback. #8168

• Performance: The equals and hashCode or records are now fully optimized, record components are no longer registered as "unsafe accessed". The same holds for VarHandle usages as long as the VarHandle is a compile time constant.
  [GR-51106] Represent field offsets as a FieldOffsetNode during static analysis. #8215
  [GR-51194] Do not mark objects as reachable that are only used in FrameState. #8157

• Layered native images:
  [GR-51602] [GR-49708] Add "open-world" typecheck. #8315
  Persisting and reloading of shadow heap
  [GR-51211] Preparations for multiple image heaps at runtime. #8189
  Loading of layered images, i.e., combining multiple image heaps at startup
  Introduce "type reached" to replace "type reachable", piggybacking on class initialization status
  [GR-51059] Resolve configuration conditions during JSON parsing. #8250

• Compatibility
  [GR-41558] Support for lambda class predefinition on Native Image #8309 Necessary to run the Renaissance benchmarks that use Spark.

• Cleanups:
  Remove IntrinsifyMethodHandleInvocationPlugin usage with runtime compilation
  Instead of removing SpawnIsolates immediately, we want to bring -H:-SpawnIsolates closer to the "normal" mode by always using a heap-base register.
  [GR-51363] Remove ExtendedAsserts option. #8324
  [GR-51520] Remove the old class initialization strategy. #8323
  [GR-51858] Simplify handling of original method and type lookup. #8325
  [GR-51637] Directly use JVMCI for constant pool accesses #8275
  [GR-50866] Remove single threaded mode (-H:-MultiThreaded). #8270
  [GR-51561] Remove unncessary SnippetReflectionProvider arguments and fields. #8246
  [GR-44538] Remove old heap dump implementation. #8249

• Monitoring / tools:
  [GR-47109] Support JFR event ObjectAllocationSample. #8316
  [GR-48683] Add JFR event OldObjectSample. #8251
  [GR-51629] Add support for JFR -XX:FlightRecorderOptions. #8254

Deep Dive: JFR and native memory tracking

by @roberttoyonaga

[roberttoyonaga]

Native Memory Tracking NMT

Relevant issue: #7631
Relevant PRs: #7669 #7883