java.lang.management.RuntimeMXBean not module aware

[Volker Simonis]

On Tue, Mar 7, 2017 at 10:06 AM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> On 07/03/2017 08:32, Volker Simonis wrote:
>
>> Hi,
>>
>> java.lang.management.RuntimeMXBean offers methods like getClassPath(),
>> getLibraryPath() and even getBootClassPath() if
>> isBootClassPathSupported() returns true. While
>> isBootClassPathSupported() has been changed in jdk9 to always return
>> false (although the VM still supports -Xbootclasspath/a) no additional
>> methods have been added to RuntimeMXBean to query the new module path.
>>
>> Is this intentional? I think RuntimeMXBean should contain at least a
>> new method getModulePath() wich returns the VMs module path. Looking
>> at the latest spec [1] I couldn't find such an addition. Will this be
>> added in the final version or are there some reasons against having
>> getModulePath() in RuntimeMXBean?
>>
>> Exposing further information trough RuntimeMXBean like the one
>> provided by the --upgrade-module-path, --add-modules, --limit-modules,
>> --list-modules could be interesting/useful as well.
>>
> Fair point although many of the existing methods are just convenience
> methods (they are equivalent to invoking System.getProperty). RuntimeMXBean
> also defines getSystemProperties to get all the system properties and so a
> management tool does have a way to get the module path, upgrade module path,
> and main module/main class if needed. RuntimeMXBean also defines
> getInputArguments so there is a way (where supported) to see VM options such
> as --limit-options.
>

OK, but shouldn't the RuntimeMXBean also provide an ability to list
all the observable modules (like --list-modules)? Before jdk9
something similar could be achieved by scanning sun.boot.class.path,
but that possibility is gone now.

> That said, I could see one of the platform MXBeans (maybe RuntimeMXBean)
> exposing access to the modules in the runtime. It's an area that was looked
> at briefly in the early exploratory phase of Project Jigsaw but not in
> recent time.

Yes, that's probably what I meant :)

>
> -Alan.