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

[Thomas Stüfe]

Hi Serguei,

thank you for your review!

You are right, a regression test makes sense here. I wrote one. See
updated webrev (only added the test, nothing else did change):

http://cr.openjdk.java.net/~stuefe/webrevs/8203343-VM.metaspace-show-reflection-invocation-targets/webrev.01/webrev/

I am re-running the jdk-submit tests.

Thanks & Best Regards, Thomas

On Tue, Jun 12, 2018 at 11:01 PM, serguei.spitsyn at oracle.com
<serguei.spitsyn at oracle.com> wrote:
> Hi Thomas,
>
> It looks good to me.
> But I'm not an expert in the area of Generated Accessors.
>
> How was this tested?
> Does it make sense to add a unit test for this?
>
> Thanks,
> Serguei
>
>
>
> On 6/6/18 09:05, Thomas Stüfe wrote:
>>
>> 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
>
>