RFR 8153629: Need to cover JVMTI's GetOwnedMonitorStackDepthInfo function

[Chris Plummer]

On 1/12/18 2:52 PM, serguei.spitsyn at oracle.com wrote:
> Hi Chris,
>
>
> On 1/12/18 14:31, Chris Plummer wrote:
>> Hi Serguei,
>>
>> On 1/12/18 2:25 PM, serguei.spitsyn at oracle.com wrote:
>>> Hi Daniil,
>>>
>>> It is pretty good in general.
>>> Thank you for taking care about it!
>>>
>>> Some comments though.
>>>
>>> The test case is too trivial.
>>> I'd suggest to extend it to have at least a couple of locks in the 
>>> returned array.
>>> One way to do it would be to add a instance synchronized method and
>>> invoke it from the synchronized statement of the tested Thread.
>>> Then the verifyOwnedMonitors() can be invoked from this method.
>>>
>>> A couple of comments on the native agent.
>>>
>>> 72         // JNI_OnLoad has not been called yet, so can't possibly 
>>> be an instance of TEST_CLASS.
>>>
>>> Could you, please, rewrite this comment?
>>> Maybe just tell that there probably was an error in loading the 
>>> TEST_CLASS.
>> This was copied from my comment in GetOwnedMonitorInfoTest, which I 
>> assume this test was based on.
>
> Yes, I also assumed it was copied from the GetOwnedMonitorInfoTest.
> The comment looks incorrect and creates some confusion.
How is it incorrect? If testClass is NULL, that does imply that 
JNI_OnLoad has not been called yet, which itself implies that the object 
cannot be an instance of TEST_CLASS.
>
>
>>> What about moving the FindClass(env, TEST_CLASS) to the 
>>> verifyOwnedMonitors() function?
>>> It will make the testClass variable local.
>>>
>> Also from GetOwnedMonitorInfoTest. This is code I reworked in that 
>> test recently to fix 8191229.
>
> Yes, I remember.
>
>> These two tests should be kept consistent.
>
> I still think, making it a part of the verifyOwnedMonitors() would 
> simplify the test.
> Why do we need the testClass to be volatile and global if it is used 
> only in the context of verification?
> It generates less questions if it is local.
> We could attempt to fix the GetOwnedMonitorInfoTest as well if we want 
> this kind of consistency.
I think in this test you could make looking up testClass local to 
verifyOwnedMonitors() since calling it is under our control.  In 
GetOwnedMonitorInfoTest, there is no place to safely make it local, 
because we need testClass during a JVMTI callback, and we can't always 
correctly look up TEST_CLASS in the callback. That's why the lookup was 
moved as part of 8191229 into JNI_OnLoad.

thanks,

Chris
>
> Thanks,
> Serguei
>
>
>> Chris
>>>  200 fprintf(stderr, "VerifyOwnedMonitors: FAIL: 
>>> stackDepthInfo[0].stack_depth should be 1.\n");
>>>
>>>  207         fprintf(stderr, "VerifyOwnedMonitors: FAIL: 
>>> monitorCount should be 1.\n");
>>>
>>>
>>> It'd better to rephrase the messages above to tell about actual 
>>> values vs expected.
>>> It normally simplifies the analysis of failures as there is no need 
>>> to find
>>> what values were printed before and that they are exactly what 
>>> needed for comparison.
>>>
>>> Thanks,
>>> Serguei
>>>
>>>
>>>
>>> On 1/11/18 17:45, Daniil Titov wrote:
>>>> Hello,
>>>>
>>>> Please review the following fix that adds a jtreg test for 
>>>> GetOwnedMonitorStackDepthInfo JVMTI function.
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8153629
>>>> Webrev: http://cr.openjdk.java.net/~dtitov/8153629/webrev.00
>>>>
>>>>
>>>> The tests ran successfully with Mach5.
>>>>
>>>> Best regards,
>>>> Daniil
>>>>
>>>>
>>>
>>
>>
>