RFR 8062116: JVMTI GetClassMethods is Slow

[Jeremy Manson]

Thanks, Coleen - I saw that you committed it, but the change had a long
contributed-by line, so I wasn't sure whether you were the right person to
reach out to.

Jeremy

On Fri, Oct 31, 2014 at 8:36 AM, Coleen Phillimore <
coleen.phillimore at oracle.com> wrote:

>
> Jeremy,
> I will review and sponsor this for you since I wrote the original code.
> Thanks,
> Coleen
>
>
> On 10/30/14, 1:02 PM, Jeremy Manson wrote:
>
>> There's a significant regression in the speed of JVMTI GetClassMethods in
>> JDK8. I've tracked this down to allocation of jmethodids in a tight loop.
>> The issue can be addressed by preallocating enough space for all of the
>> jmethodids when starting the operation and not iterating over all of the
>> existing jmethodids when you allocate a new one.
>>
>> A patch is here:
>>
>> http://cr.openjdk.java.net/~jmanson/8062116/webrev.00/
>>
>> A reproducible test case can be found here:
>>
>> http://cr.openjdk.java.net/~jmanson/8062116/repro/
>>
>> It's a benchmark, though: I have no idea how to turn it into a test.
>>
>> For whoever reviews it: can you explain to me why it is okay that this
>> code
>> reuses jmethodIDs (in JNIMethodBlock::add_method?  I can imagine a lot of
>> problems stemming from accidental reuse.
>>
>> Jeremy
>>
>
>