Claes discovered that the Long cache is not populated during CDS dump time during the work for JDK-8213033. As a result, the Long cache and associated Long objects cannot be archived.

Archiving the Long cache is beneficial for string concatenation, for example. As we now support archiving subgraphs in the closed archive heap region, archiving the remaining primitive box caches can help providing more memory sharing at runtime.

During CDS dump time, we can force initialization for classes with registered subgraph archiving entry field for the boot loader. Running the initializers can populate the static fields for those classes, including the primitive box caches. As a result, it will allow the primitive caches to be archived at dump time.