RFR(s): 8203343: VM.{metaspace|classloaders|classhierarchy...} jcmd should show invocation targets for Generated{Method|Constructor}AccessorImpl classes

[Thomas Stüfe]

Dear all,

may I please have feedback and if possible reviews for this small addition:

CR: https://bugs.openjdk.java.net/browse/JDK-8203343
Webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8203343-VM.metaspace-show-reflection-invocation-targets/webrev.00/webrev/

(Note: this patch goes atop of
https://bugs.openjdk.java.net/browse/JDK-8203682, which is currently
up for RFR).

---

When analyzing situations involving a lot of reflection, one often
stares at walls of "GeneratedXXXAccessorXXX" classes. These names are
generated and not at all helpful in analyzing the problem (e.g. which
component in a server node does this much reflection and hence uses so
much metaspace).

This patch adds the ability to print out invocation targets
additionally to class names if the class is a generated accessor - for
now this ability has been added to VM.metaspace, VM.classloaders and
VM.class_hierarchy.

Example output from "VM.class_hierarchy":

<snip>
|--jdk.internal.reflect.MagicAccessorImpl/null
<snip>
|  |--jdk.internal.reflect.ConstructorAccessorImpl/null
|  |  |--jdk.internal.reflect.GeneratedConstructorAccessor18/0x00007f9ee8350c10
(invokes: org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessorRegistrar::<init>
()V)
|  |  |--jdk.internal.reflect.GeneratedConstructorAccessor17/0x00007f9ee8349c00
(invokes: org/springframework/boot/context/properties/EnableConfigurationPropertiesImportSelector$ConfigurationPropertiesBeanRegistrar::<init>
()V)
<snip>
|  |--jdk.internal.reflect.MethodAccessorImpl/null
|  |  |--jdk.internal.reflect.GeneratedMethodAccessor23/0x00007f9ec8329b60
(invokes: org/apache/tomcat/util/modeler/AttributeInfo::setIs (Z)V)
|  |  |--jdk.internal.reflect.GeneratedMethodAccessor22/0x00007f9ee831bc70
(invokes: org/springframework/boot/autoconfigure/SpringBootApplication::exclude
()[Ljava/lang/Class;)
<snip>

See here more examples:

"VM.class_hierarchy"
http://cr.openjdk.java.net/~stuefe/webrevs/8203343-VM.metaspace-show-reflection-invocation-targets/example-VM.class_hierarchy.txt

"VM.classloaders show-classes"
http://cr.openjdk.java.net/~stuefe/webrevs/8203343-VM.metaspace-show-reflection-invocation-targets/example-VM.classloaders.txt


----

Note: I am not sure if this is a fit for hotspot-runtime or
serviceability. Sorry for crossposting.

Thank you,

Thomas