On 21/10/2021 10:49, Jaikiran Pai wrote:
:
Digging into it, it appears that since the ModuleDescriptor#equals()
calls equals() on enum types (in this specific case on
ModuleDescriptor.Requires.Modifier) and since enum type equality is
implemented as identity checks, those identity checks are surprisingly
failing. More specifically ModuleDescriptor.Requires.Modifier.MANDATED
== ModuleDescriptor.Requires.Modifier.MANDATED is equating to false
because at runtime I see that two different instances of
ModuleDescriptor.Requires.Modifier.MANDATED have been loaded (by the
same boot module classloader). Although I use
ModuleDescriptor.Requires.Modifier.MANDATED as an example, the same is
reproducible with other enum values like
ModuleDescriptor.Requires.Modifier.TRANSITIVE.
This appears to be specific to CDS since running the above program with:
java -Xshare:off EnumEquality
succeeds and the ModuleDescriptor equality check passes.
In short, it looks like there is some general issue with CDS and
equality checks with enums and perhaps deserves a separate JBS issue?
I've asked Ioi Lam to comment on this, off-hand I'm not aware of any
issues with CDS here but it may be related to the archiving of object
graphs.
-Alan
