Native Image Hosted and Runtime Options

Along with all the options listed in the Options guide, Native Image also distinguishes hosted and runtime options.

  • Hosted options: configure a native image build, i.e., influence what is put into the image and how the image is built. These are set using the prefix -H: on the command line.

  • Runtime options: get their initial value during an image generation, using the prefix -R: on the command line for the native image builder. At runtime, the default prefix is -XX: (but this is application-specific and not mandated by Native Image).

For developer documentation on how to define and use options, read the documentation of the package.

List of Useful Options #

Graph Dumping #

Native Image re-used the GraalVM options for graph dumping, logging, counters, and everything else in the GraalVM debug environment. These GraalVM options can be used both as hosted options (if you want to dump graphs of the native image builder), and as runtime options (if you want to dump graphs during dynamic compilation at runtime).

The GraalVM compiler options that work as expected include Dump, DumpOnError, Log, MethodFilter, and the options to specify file names and ports for the dump handlers.

For example:

  • To dump the compiler graphs of the native image builder: -H:Dump= -H:MethodFilter=ClassName.MethodName.

  • To dump the compile graphs at runtime, specify the dump flags at runtime: -XX:Dump= -XX:MethodFilter=ClassName.MethodName.

Debug Options #

These options enable additional checks in the generated executable to help with debugging:

  • -H:[+|-]HostedAssertions enables or disables Java assert statements in the native image builder. This flag is translated to either -ea -esa or -da -dsa for the HotSpot VM.
  • -H:[+|-]RuntimeAssertions enables or disables Java assert statements at run time.
  • -H:TempDirectory=FileSystemPath generates a directory for temporary files during a native image generation. If this option is specified, the temporary files are not deleted so that you can inspect them after the native image generation.

Control the Main Entry Points #

  • -H:Kind=[EXECUTABLE | SHARED_LIBRARY]: generates an executable with a main entry point, or a shared library with all entry points that are marked via @CEntryPoint.
  • -H:Class=ClassName: the class containing the default entry point method. Ignored if Kind == SHARED_LIBRARY.
  • -H:Projects=Project1,Project2: the project that contains the application (and transitively all projects that it depends on).
  • -H:Name=FileName: the name of the executable file that is generated.
  • -H:Path=FileSystemPath: the directory where the generated executable is placed.