RFR: 8267796: vmTestbase/nsk/jvmti/scenarios/hotswap/HS201/hs201t002/TestDescription.java fails with NoClassDefFoundError

[Chris Plummer]

On Thu, 24 Feb 2022 12:44:18 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> The fix adds workaround in hs201t001a class like we have in hs201t001 test to avoid class loading while the test do single stepping/pop frame.
> Also fixed a number of issues in the test.

test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/hotswap/HS201/hs201t002.java line 84:

> 82:         thread.start();
> 83: 
> 84:         // enable events requires live thread

I think a more detailed comment could be used here. Something like:

// setThread(thread) enables JVMTI events, and that can only be done on a live thread,
// so wait until the thread has started.

test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/hotswap/HS201/hs201t002/hs201t002.cpp line 107:

> 105:     }
> 106: 
> 107:     if (!NSK_VERIFY(readNewBytecode(jvmti_env, newClassSize, newClassBytes))) {

For simple types I don't care for C++ pass-by-ref arguments. At the call site it just looks like the values are being passed in. When I first read this it didn't look right to me since they are uninitialized, so I had to look at readNewBytecode() to see what was going on.

test/hotspot/jtreg/vmTestbase/nsk/jvmti/scenarios/hotswap/HS201/hs201t002/hs201t002.cpp line 368:

> 366:         if (threadName != NULL) {
> 367:             jvmti->Deallocate((unsigned char*)threadName);
> 368:         }

callbackException() and callbackExceptionCatch() seem to be identical other than callbackException() taking a couple of extra unused arguments. They should probably both just call a shared function.

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PR: https://git.openjdk.java.net/jdk/pull/7607