JMX agents and Jigsaw

[Alan Bateman]

On 24/07/2015 10:12, Ron Pressler wrote:
> OK, but assuming I have no control over the user's runtime image, am I 
> correct that programmatically starting the local JMX agent as I do now 
> (without the Attach API) will no longer be possible in Java 9?
>
I'm not aware of any supported way of doing this in any JDK release, at 
least not without using Runtime.exec or ProcessBuilder to invoke the 
jcmd tool which might or might not be present.

If you have code making direct use of JDK-internal classes such as 
sun.management.Agent then it fail at both compile-time and run-time with 
JDK 9 once the module system goes in. There will be a command-line 
option to work around this but no guarantees of course as 
sun.management.Agent might not exist, might be refactored significantly, 
etc.

You probably know this already but you can start your own 
JMXConnectorServer if you want. Also you don't need the JMX agent to 
access the platform MXBeans in the current runtime.

As regards tools using the attach API then then moving them to modules 
means they can have an explicit dependency on the jdk.attach module. 
This is good because it means they won't even start on a run-time that 
doesn't the jdk.attach module. Also if you get to create your own 
run-time image and want to include one or these tools then it will 
ensure that the jdk.attach module is also linked in.

-Alan