8381900: Test vmTestbase/nsk/jvmti/scenarios/allocation/AP03/ap03t001 does not handle frequent GC gracefully

[jsikstro]

Hello,

In the development of Automatic Heap Sizing (AHS) for ZGC we have seen vmTestbase/nsk/jvmti/scenarios/allocation/AP03/ap03t001 fail intermittently. The main thing in AHS affecting this test is the number of GCs being run. The ap03t001 test seems to not be able to reliably handle GC at any moment.

A naive solution to this problem is to just increase the min/initial heap size to give the test more headroom, but I think we should go with a more robust approach. What we're seeing in failing runs is that not only the "holder" object is beeing freed, but the test-object itself as well.

public static int run(String argv[], PrintStream out) {
    return new ap03t001().runThis(argv, out);
}

// ...

private int runThis(String argv[], PrintStream out) {
    // ...
    ap03t001 holder = new ap03t001();
    // ...
}

I propose we ignore ObjectFree events after having verified that the holder object has been resurrected into the catcher object, which is what this test is all about. Another alternative could be to disable ObjectFree events entirely after we're done, but I think this approach is easier to follow.

Testing:

• Local testing with AHS, and in mainline, that this test passes when running a bunch of GC.

---

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Issue

• JDK-8381900: Test vmTestbase/nsk/jvmti/scenarios/allocation/AP03/ap03t001 does not handle frequent GC gracefully (Bug - P4)

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