RFR 6642881: Improve performance of Class.getClassLoader()

[Coleen Phillimore]

On 6/16/14, 1:50 PM, roger riggs wrote:
> Hi Colleen,
>
> In Class.java, if only the VM creates Class objects  (comment at line 
> 681),
> and it does not use the constructor then the code (line 136) in the 
> constructor
> to set classloader is misleading and deserves a comment.

Thanks, Roger.  How about this comment?

     /*
      * Constructor. Only the Java Virtual Machine creates Class
      * objects, but this constructor prevents a warning that 
classLoader is not
      * initialized.
      */
     private Class(ClassLoader loader) {
         classLoader = loader;
     }

Coleen
>
> Roger
>
> On 6/16/2014 1:45 PM, Lois Foltan wrote:
>> Hi Coleen,
>> This looks good.
>> Lois
>>
>> On 6/16/2014 11:42 AM, 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.
>>>
>>> Tested with jck lang, vm, api/java_lang tests with/without jdk 
>>> change, nsk vm.quick.testlist and hotspot jtreg tests, and jprt.
>>>
>>> Thanks,
>>> Coleen
>>>
>>>
>>
>