RFR: 8258061: Improve diagnostic information about errors during class redefinition

[Coleen Phillimore]

On Thu, 17 Dec 2020 00:44:18 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

> The error code during class redefinition might be not enough to easily diagnose the problem. Some more logging might be useful to understand it. I encountered this problem when redefined methods with lambda usage.
> I run all existing tests with enabled logging and sanity verified error messages.

src/hotspot/share/prims/jvmtiRedefineClasses.cpp line 935:

> 933:        the_class->super()->name() !=
> 934:        scratch_class->super()->name())) {
> 935:     log_trace(redefine, class, normalize)

I think these would be useful to users so that these should be made log_info(redefine). All the other redefinition logging is useful for developers in debugging redefinition, and a user wouldn't really be able to follow the output unless they are very knowledgeable.  Making this log_info(redefine) would let them see this without the noise of the other output.

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PR: https://git.openjdk.java.net/jdk/pull/1811