RFR 8207778: Add locking to ModuleEntry and PackageEntry tables

[coleen.phillimore at oracle.com]

I think this looks really good.  Thank you for making this change!
Coleen

On 8/9/18 2:10 PM, Harold David Seigel wrote:
> Hi,
>
> Please review this fix for JDK-8207778.  Instead of adding additional 
> and unneeded locking to the ModuleEntry and PackageEntry tables, the 
> ClassLoaderDataGraph unloading code was restructured to simplify 
> changing SystemDictionary::do_unloading() to safely scan these tables 
> either by taking a lock or during a safepoint.
>
> Also, asserts for other tables scanned by 
> SystemDictionary::do_unloading() were changed from requiring a 
> safepoint to requiring either a lock or a safepoint.
>
> Open Webrev: http://cr.openjdk.java.net/~hseigel/bug_8207778/webrev/
>
> JBS Bug:  https://bugs.openjdk.java.net/browse/JDK-8207778
>
> This fix was regression tested by running Mach5 tiers 1 and 2 tests 
> and builds on Linux-x64, Windows, and Mac OS X, running tiers 3-5 
> tests on Linux-x64, and by running JCK-11 API, Lang and VM tests on 
> Linux-x64.
>
> Thanks, Harold
>