RFR: 8284313: Improve warning messages when CDS archive fails to load

[David Holmes]

On Wed, 10 Aug 2022 17:19:51 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

> Please review this change for adding more helpful messages when a CDS archive has failed to load without CDS logging being enabled.
> 
> e.g. warning for mismatch class paths between dump time and run time:
> `[warning][cds] shared class paths mismatch (hint: enable -Xlog:class+path=info to diagnose the failure)`
> 
> warning if a timestamp of a jar file has been changed during run time:
> `[warning][cds] app.jar timestamp has changed.`
> 
> Passed mach5 tiers 1,2,3 testing.

src/hotspot/share/cds/filemap.cpp line 468:

> 466:         log_warning(cds)("%s timestamp has changed.", name);
> 467:       } else {
> 468:         log_warning(cds)("%s size has changed.", name);

Shouldn't these be incorporated into the message the fail_continue will report under log_info? By themselves the log_warning output will look odd, with no context.

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PR: https://git.openjdk.org/jdk/pull/9823