RFR (S) 8075030: JvmtiEnv::GetObjectSize reports incorrect java.lang.Class instance size

[Aleksey Shipilev]

So I think there is consensus this fix is okay. I am going to push it
soon via jdk9/hs, if there are no further objections.

On 06/02/2016 11:15 AM, serguei.spitsyn at oracle.com wrote:
> Aleksey, I'm Ok with the change too.

On 6/1/16 23:59, Staffan Larsen wrote:
> I think the change is fine, but I also think we should add a release
> note about the change to avoid surprises.

On 6/1/16 10:19, Coleen Phillimore wrote:
> This seems like a pretty straightforward fix. [...] Thanks for fixing
> this and the tests.

Thanks,
-Aleksey


>>>>>> On 5/31/16 00:40, Aleksey Shipilev wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Please review a tiny fix in GetObjectSize:
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8075030
>>>>>>> http://cr.openjdk.java.net/~shade/8075030/webrev.01/
>>>>>>> <http://cr.openjdk.java.net/%7Eshade/8075030/webrev.01/>
>>>>>>>
>>>>>>> I think this is a leftover from Metaspace work.
>>>>>>>
>>>>>>> For some reason, JvmtiEnv::GetObjectSize has a special case for
>>>>>>> java.lang.Class: it returns the Klass* size, not the java.lang.Class
>>>>>>> instance size. This is incorrect: Klass* is indeed referenced from
>>>>>>> java.lang.Class.metadata field, but the instance size itself does
>>>>>>> not
>>>>>>> depend on metadata size. This confuses Instrumentation.getObjectSize
>>>>>>> users.
>>>>>>>
>>>>>>> Testing: new test; RBT, :hotspot_compiler, :hotspot_gc,
>>>>>>> :hotspot_runtime, :hotspot_serviceability, :hotspot_misc,
>>>>>>> :jdk_management, :jdk_instrument, :jdk_jmx, :jdk_jdi, :svc_tools.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> -Aleksey