RFR(S): 8191229: serviceability/jvmti/GetOwnedMonitorInfo/GetOwnedMonitorInfoTest.java fails with NoClassDefFoundError

[Chris Plummer]

I didn't see any other suspicious uses of FindClass in the jvmti jtreg 
tests.

Chris

On 12/6/17 3:33 PM, serguei.spitsyn at oracle.com wrote:
> Hi Chris,
>
> It looks good to me.
> I wonder if we have other similar cases like this in the JVMTI tests.
>
> Thanks,
> Serguei
>
>
> On 12/6/17 14:38, Chris Plummer wrote:
>> Hello,
>>
>> Please review the following:
>>
>> https://bugs.openjdk.java.net/browse/JDK-8191229
>> http://cr.openjdk.java.net/~cjplummer/8191229/webrev.00/
>>
>> The test is testing contended monitor support. After registering the 
>> callback, it gets an unexpected notification of a contended monitor, 
>> which is happening while the finalizer thread is running. In the 
>> callback the test does a FindClass to find a test class, but the 
>> classloader context is not correct when the finalizer thread is 
>> current, so FindClass fails and leaves an exception pending (probably 
>> blowing away the finalzer thread) and also (separately) causes the 
>> test to fail. It's unknown why this callback is suddenly being 
>> triggered, but the callback itself is not a bug, and the test needs 
>> to defend against it.
>>
>> The fix is to lookup the test class during test initialization and 
>> keep it cached, rather than look it up every time there is a 
>> contended monitor callback.
>>
>> thanks,
>>
>> Chris
>