JMC with Static Portable JRE 11

Erik Gahlin erik.gahlin at
Wed Nov 20 18:51:02 UTC 2019

The jdk.attach module is needed if you want to discover another Java 


On 2019-11-20 19:44, Mario Torre wrote:
> The API for is new, and also all the others were before
> accessible through the tools.jar if I recall correctly, since by
> default the jre has been replaced with the modular jdk it's possible
> our scripts omit some libraries? If I remember correctly Jiri said
> that the jre is created "manually", perhaps some of the API that's
> supposed to be included isn't and it's only found in the full jvm.
> You should be able to check this by grepping for "" in
> the binary tree and see the difference between the two builds.
> Cheers,
> Mario
> On Wed, Nov 20, 2019 at 7:17 PM Jie Kang <jkang at> wrote:
>> Hey Alex, Mario,
>> I just wanted to give a quick status update to clarify that I am going
>> to get to the bottom of this.
>> I tried to run JMC with the static JRE 11 build on Linux and got the
>> same issue with being unable to see JVMs on the system. JMC on launch
>> warns:
>> WARNING: Unknown module: specified to --add-exports
>> WARNING: Unknown module: jdk.attach specified to --add-exports
>> WARNING: Unknown module: jdk.internal.jvmstat specified to --add-exports
>> WARNING: Unknown module: jdk.attach specified to --add-opens
>> I am assuming these are needed for the JVM discovery mechanism. I will
>> see how the static builds are made in openjdk.  Maybe there's an
>> alternative API that the JRE 11+ provides that JMC can use instead?
>> Otherwise we can conclude that JMC will not have discovery capability
>> with JRE 11, similar to before modules were introduced. In this
>> situation it can still be used with JRE to open and analyze JFR files
>> on disk.
>> Regards,
>> Jie Kang
> --
> Mario Torre
> Associate Manager, Software Engineering
> Red Hat GmbH <>
> 9704 A60C B4BE A8B8 0F30  9205 5D7E 4952 3F65 7898

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