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

[Chris Plummer]

On 12/6/17 6:47 PM, David Holmes wrote:
> Hi Chris,
>
> On 7/12/2017 8:38 AM, 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/
>
> I expected to see the initialization done in JNI_OnLoad, not in a new 
> init() method.
I was worried it wouldn't work because of JDK-8188052, but I guess that 
only impacts JNI_OnUnload. I can change it to init from JNI_OnLoad().

Chris
>
> David
> -----
>
>> 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