On 01.03.14 21:55, Stefan Marr wrote:
Hi:
On 01 Mar 2014, at 19:44, Alexandre Bergel <[email protected]> wrote:
The VM is a formidable thing in which everything happen. Exposing to the image
what’s going on in it is really pushing the innovation.
Perhaps something that could be relevant in case someone decides to implement
such an interface in Cog:
Just one, pretty old example:
http://docs.oracle.com/javase/6/docs/platform/jvmti/jvmti.html#EventIndex
You can get access to many different information in terms of ‘events’ on the
JVM.
For building a profiler, more than sufficient. And, at least in my personal
opinion also something that would be desirable for Cog, perhaps in a slightly
more modern design, but with a similar flavor.
Oracle itself describes JVMTI as too intrusive for production use [1].
They built their own proprietary solution called Flight Recorder [2] [3]
(Oracle marketing names) which AFAIK is based on JRockit technology.
They are confident enough about it to explicitly recommend it for
production use. They claim the overhead is about 2 to 3 %. And yes, it's
a commercial feature for production and you have to unlock with:
-XX:+UnlockCommercialFeatures
It has a horrible UI but it's quite a nice tool.
[1]
http://www.oracle.com/technetwork/java/javaseproducts/mission-control/java-mission-control-wp-2008279.pdf
[2]
http://download.oracle.com/technology/products/missioncontrol/updatesites/base/5.2.0/eclipse/
[3]
http://docs.oracle.com/javase/7/docs/technotes/guides/jfr/usingjfr.html
Cheers
Philippe
