RFR 8062116: JVMTI GetClassMethods is Slow

[David Holmes]

Adding serviceability as they own JVMTI.

David

On 31/10/2014 3:02 AM, 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
>