12 RFR(S) 8215205: javaVFrame much slower than vframeStream

[Mandy Chung]

The change looks good.

It seems useful to add a microbenchmark in getting ACC so that we can 
proactively compare the performance for relevant stackwalk change.  With 
JEP 230, the microbenchmarks are in the jdk test/micro directory and 
it's very handy to run microbenchmarks.  I'm not sure if one already 
exists; if not, it's good to follow up with a new JBS and add one.

Mandy
[1] http://openjdk.java.net/jeps/230

On 12/17/18 2:40 PM, dean.long at oracle.com wrote:
> https://bugs.openjdk.java.net/browse/JDK-8215205
> http://cr.openjdk.java.net/~dlong/8215205/webrev
>
> This change allows a stackwalk to continue using the faster 
> vframeStream iterator, but changing to a javaVFrame lazily as needed.  
> It introduces a new API
>
>   javaVFrame* vframeStreamCommon::asJavaVFrame()
>
>
> The first user of this API will be JDK-8214329, which is why this 
> issue is a P3.
>
> dl