RFR 8190359: Reduce the number of recorded klass dependencies

[Ioi Lam]

Hi Harold,

Why is this needed

  336   if (from_cld == to_cld ...

It seems like it's already checked by here

  350     if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {

It's probably explained by this

  348     assert(from != to || from_cld->is_anonymous(), "sanity check");

... but I think this is a rather tricky area so either (a) more comments 
might be needed in the source code, or (b) simplify the code so it 
requires less explanation.

Also, I wonder if it's possible to add a new test case for this.

Thanks

- Ioi



On 1/30/18 10:38 AM, harold seigel wrote:
> Hi,
>
> Please review this RFR for JDK-11 to reduce the number of class 
> dependencies recorded by the VM.  The change primarily does this by 
> not recording dependencies to classes that are loaded by a builtin 
> class loader and are not anonymous.  These classes never get unloaded, 
> so no recorded dependency is needed.
>
> Additionally, the change simplifies the code that deals with when the 
> classes have the same class loader and when the dependency is to a 
> class loaded by a parent loader.
>
> Open Webrev: 
> http://cr.openjdk.java.net/~hseigel/bug_8190359/webrev/index.html
>
> JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8190359
>
> The change was tested with JPRT, Mach 5 tier1 - tier5 tests, and 
> non-colocated tonga tests.  Additionally, print statements were 
> temporarily added to the code and the output analyzed to check that 
> dependencies were being correctly recorded or not recorded.
>
> Thanks, Harold