RFR: 8318026: jcmd should provide access to detailed JVM object information [v13]

[Serguei Spitsyn]

On Thu, 4 Apr 2024 12:46:26 GMT, Kevin Walls <kevinw at openjdk.org> wrote:

>> Introduce the jcmd "VM.inspect" to implement access to detailed JVM object information.
>> 
>> Not recommended for live production use.  Requires UnlockDiagnosticVMOptions and not included in jcmd help output, to remind us this is not a general-purpose customer-facing tool.
>
> Kevin Walls has updated the pull request incrementally with one additional commit since the last revision:
> 
>   VMInspectTest update

The fix looks good to me. I've posted a couple of nits. Do I understand it right that introducing an unlocking option is going to be addressed separately?

test/hotspot/jtreg/serviceability/dcmd/vm/VMInspectTest.java line 189:

> 187:         // so make a few attempts.
> 188:         BigInteger ptr = null;
> 189:         for (int i=0; i < OBJECT_TRIES; i++) {

Nit: Need spaces around `=`.

test/hotspot/jtreg/serviceability/dcmd/vm/VMInspectTest.java line 224:

> 222:                 expected = "is a good oop";
> 223:             }
> 224:         }

Nit: The lines 219-223 can be simplified:
    `expected = isGenZGC ? "is a zaddress" : "is a good oop";

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Marked as reviewed by sspitsyn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17655#pullrequestreview-1981143486
PR Review Comment: https://git.openjdk.org/jdk/pull/17655#discussion_r1552427826
PR Review Comment: https://git.openjdk.org/jdk/pull/17655#discussion_r1552434356