RFR 6642881: Improve performance of Class.getClassLoader()
Alan Bateman
Alan.Bateman at oracle.com
Mon Jun 16 18:06:21 UTC 2014
On 16/06/2014 16:42, Coleen Phillimore wrote:
> Summary: Add classLoader to java/lang/Class instance for fast access
>
> In order to improve performance of Class.getClassLoader() in a way to
> allow the compilers to automatically optimize this call, I added the
> classLoader to the instance of java/lang/Class. For microbenchmarks,
> this results in a 98% improvement, which was expected. For Oracle
> internal applications, this results in a 10-12% improvement on
> solaris/sparc. The increase in size of java/lang/Class can be offset
> by other changes (removing constant pool lock, or removing signers).
>
> See bug link https://bugs.openjdk.java.net/browse/JDK-6642881 and
> associated linked bugs for more details.
>
> open webrev at http://cr.openjdk.java.net/~coleenp/6642881_hotspot/
> open webrev at http://cr.openjdk.java.net/~coleenp/6642881_jdk/
>
> There is both hotspot and jdk changes for this change. The hotspot
> changes can work without the jdk changes (check for optional field),
> but not vice-versa. I'll file another bug (and compatibility request)
> to remove JVM_GetClassLoader from hotspot.
>
The jdk changes look okay to me. One thing that I mentioned to Coleen
off-list is that we have some dead code in the old verifier that uses
JVM_GetClassLoader - I don't know the history to that but it should be
checked and probably removed.
-Alan
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