RFR(XS) 8191924: Adjust DelegatingClassLoader's metadata space sizing algorithm

[coleen.phillimore at oracle.com]

This change looks good!
Coleen

On 3/13/18 1:22 PM, Zhengyu Gu wrote:
> Please review this simple patch, that applies the same sizing 
> algorithm for anonymous class loader [1] to delegating class loader.
>
> Delegating class loader has similar memory usage pattern as anonymous 
> class loader. By applying the same sizing logic, it reduces about the 
> same percentage of wasted memory as anonymous class loader's metedata 
> space.
>
> Ex.
>
> Before:
> ClassLoader: jdk/internal/reflect/DelegatingClassLoader
>   Metadata   capacity=      5.00KB used=      1.55KB free= 3.45KB 
> waste=      0.04KB
>   Class data capacity=      1.00KB used=      0.58KB free= 0.42KB 
> waste=      0.00KB
>
> After:
> ClassLoader: jdk/internal/reflect/DelegatingClassLoader
>   Metadata   capacity=      2.00KB used=      1.55KB free= 0.45KB 
> waste=      0.04KB
>   Class data capacity=      1.00KB used=      0.58KB free= 0.42KB 
> waste=      0.00KB
>
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8191924
> Webrev: http://cr.openjdk.java.net/~zgu/8191924/webrev.00/
>
> Test:
>
>   hotspot_runtime on Linux x64 (fastdebug and release)
>
>
> [1]https://bugs.openjdk.java.net/browse/JDK-8190729
>
> Thanks,
>
> -Zhengyu
>