Accessing module internals from bytecode rewriting agent

Alan Bateman Alan.Bateman at
Tue Apr 25 06:22:30 UTC 2017

On 25/04/2017 04:26, Martin Buchholz wrote:

> :
> java.lang.IllegalArgumentException: illegal lookupClass: class
> java.util.PriorityQueue
> Bytecode rewriting agents have the power to inject code into classes; they
> should somehow also be able to reflectively inspect those same classes!
> But how?  We ran into similar problems trying to port java agents at Google
> to jdk9.
On the general point: agents (both java and JVM TI agents) can redefine 
any module in support of instrumentation and any amount of deep 
reflection that the agent might do. So I wouldn't expect too many issues 
although some java agents may need updates to work on JDK 9 without 
encapsulation busting command line options.

On Byteman, Andrew Dinn has been working with us on jigsaw-dev on the 
agent support. From the stack trace then I suspect the issue you are 
running into is that Byteman has also changed to use the new reflection 
API (java.lang.invoke) and is running into a long standing check to 
prevent full power lookups to full privileged classes from leaking. 
Andrew brought this up on jigsaw-dev [1] a few days ago and we could 
probably move that thread to core-libs-dev.



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