RFR: 8308762: Metaspace leak with Instrumentation.retransform

[Coleen Phillimore]

On Thu, 6 Jul 2023 05:18:01 GMT, Jean-Philippe Bempel <jpbempel at openjdk.org> wrote:

> Fix a small leak in constant pool merging during retransformation of a class. If this class has a catch block with `Throwable`, the class `Throwable` is pre-resolved in the constant pool, while all the other classes are in a unresolved state. So the constant pool merging process was considering the entry with pre-resolved class as different compared to the destination and create a new entry. We now try to consider it as equal specially for Methodref/Fieldref.

ConstantPool merging is still really complicated and JVM_CONSTANT_Class/UnresolvedClass (and UnresolvedClassInError) may have changed to not track with what RedefineClasses does.  If I'm reading this correctly, we are always calling find_matching_entry() and compare_entries_to() between the merged_cp and scratch_cp.  Since we unresolve classes in merge_cp, and scratch_cp hasn't resolved anything yet, how are we getting this mismatch?  Can you post a stack trace for us?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/14780#issuecomment-1629940553