RFR(XS): 8036666: JVMTI GetObjectMonitorUsage does not return correct recursion count

Mon Mar 17 22:01:11 UTC 2014

Axel,

The changes it self looks good for me.

But it looks like the owning_thread is always NULL if
owner is NULL, so we can safely move this code
to ll.1017 and join two identical ifs together.

Also comment on ll. 1019 is misleading, could you remove it?

-Dmitry

On 2014-03-13 12:19, Siebenborn, Axel wrote:
> Hi Serguei,
> new webrev:
> http://www.sapjvm.com/as/webrevs/8036666_2/
> I should review my own changes more carefully.
> Sorry for that.
> Thanks,
> Axel
> 
> 
> 
> On 12.03.2014 18:34, serguei.spitsyn at oracle.com wrote:
>> Hi Axel,
>>
>> Thank you for the changes! It looks good, but one more place need a
>> fix (expected must be 4 now):
>>
>> 230         if (recursionCount != 4) { 231             throw new
>> AssertionError("recursions: expected 3, but was " + recursionCount); 
>> 232         }
>>
>>
>> Thanks, Serguei
>>
>>
>> On 3/12/14 8:21 AM, Siebenborn, Axel wrote:
>>> Hi Serguei, I created a new webrev:
>>>
>>> http://www.sapjvm.com/as/webrevs/8036666_1/
>>>
>>> I incorporated your suggestions and moved the test files.
>>>
>>> Thanks, Axel
>>>
>>>
>>> On 11.03.2014 20:25, serguei.spitsyn at oracle.com wrote:
>>>> On 3/11/14 12:05 PM, Staffan Larsen wrote:
>>>>> On 11 mar 2014, at 16:48, Siebenborn, Axel
>>>>> <axel.siebenborn at sap.com <mailto:axel.siebenborn at sap.com>>
>>>>> wrote:
>>>>>> Hi Seguei, I still can't upload files to the cr.openjdk
>>>>>> server. Meanwhile, I use our server for the new webrev:
>>>>>>
>>>>>> http://www.sapjvm.com/as/webrevs/8036666/
>>>>>>
>>>>>> Thanks, Axel
>>>>>>
>>>>>> Comments inline:
>>>>>>
>>>>>> On 11.03.2014 09:50,serguei.spitsyn at oracle.com
>>>>>> <mailto:serguei.spitsyn at oracle.com>wrote:
>>>>>>> Hi Axel,
>>>>>>>
>>>>>>> The webrev link is resolvable now. Thank you for taking
>>>>>>> care about your broken account on the cr.openjdk server!
>>>>>>>
>>>>>>> I have some comments on the test case ...
>>>>>>>
>>>>>>> - This is nice test, thank you for providing it!
>>>>>>>
>>>>>>> - The location of the test must be different as it is a
>>>>>>> JVMTI test: test/serviceability/jvmti/8036666  instead of
>>>>>>> test/runtime/8036666
>>>>>> I moved the test.
>>>>> Tests should avoid the bug number in the name or path and
>>>>> instead use a descriptive name. See this page for some
>>>>> background:
>>>>> https://wiki.openjdk.java.net/display/HotSpot/Naming+HotSpot+JTReg+Tests
>>>>
>>>>>
> The test files have already descriptive names.
>>>> So, it would be enough to remove the bug number from the path. 
>>>> Sorry, I had to catch it too in the first place.
>>>>
>>>> Thanks, Serguei
>>>>> Thanks, /Staffan
>>>>>>> RecursiveObjectLock,java:
>>>>>>>
>>>>>>> - A suggestion to add a synchronized method (say,
>>>>>>> nestedLock3) into the chain of calls started from the
>>>>>>> testMethod. In order to do so, the class
>>>>>>> RecursiveObjectLock needs to extend the ALock class. And
>>>>>>> the this object needs to be used in the synchronized
>>>>>>> statements and for wait()? What do you think about such
>>>>>>> test enhancement for better coverage?
>>>>>> In order to have a synchronized method in the call chain, I
>>>>>> synchronize on the "this" object.
>>>>>>> GetObjectLockCount.java:
>>>>>>>
>>>>>>> - The comment line 283 seems to be obsolete as the "param
>>>>>>> out" is not present anymore:
>>>>>>>
>>>>>>> 283      * @param out   Stream to copy to
>>>>>>>
>>>>>>>
>>>>>>> - Could you, please, add e.printStackTrace() into the catch
>>>>>>> statements at the lines 232 and 300?
>>>>>>>
>>>>>>> - A question: It seems the errThread and outThread are
>>>>>>> started a little bit late. Would it be better to start them
>>>>>>> earlier, or it was intentional?
>>>>>> You're right! I moved to code up.
>>>>>>> Some minor style-related comments (I hope, it is easy to
>>>>>>> fix this before push): - Unneeded extra empty lines:
>>>>>>> 149, 174-175, 244 - A space is missed before the '{':
>>>>>>> 180, 242, 243, 246 - Unneeded extra space after and before
>>>>>>> the "(":   235, 297 - The curly brackets '{' do not follow
>>>>>>> the common style:  142, 144
>>>>>> I hope I fixed them all and added no new style violations. Do
>>>>>> you have a tool to check this?
>>>>>>> We still need another reviewer for this fix. I'm ready to
>>>>>>> be a sponsor for it.
>>>>>>>
>>>>>>> Thanks, Serguei
>>>>>>>
>>>>>>>
>>>>>>> On 3/10/14 12:00 AM, serguei.spitsyn at oracle.com
>>>>>>> <mailto:serguei.spitsyn at oracle.com> wrote:
>>>>>>>> Hi Axel,
>>>>>>>>
>>>>>>>> The webrev link does not work now. I'll check it again
>>>>>>>> tomorrow.
>>>>>>>>
>>>>>>>> Thanks, Serguei
>>>>>>>>
>>>>>>>> On 3/7/14 1:32 AM, serguei.spitsyn at oracle.com
>>>>>>>> <mailto:serguei.spitsyn at oracle.com> wrote:
>>>>>>>>> Hi Axel,
>>>>>>>>>
>>>>>>>>> Thank you for fixing this issue. I'm reviewing it. It
>>>>>>>>> looks good in general, but a little bit more time is
>>>>>>>>> needed to look at the tests.
>>>>>>>>>
>>>>>>>>> Do you need a sponsor for pushing?
>>>>>>>>>
>>>>>>>>> Thanks, Serguei
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 3/6/14 12:08 AM, Siebenborn, Axel wrote:
>>>>>>>>>> Hi all,
>>>>>>>>>>
>>>>>>>>>> could I have a review for the following change?
>>>>>>>>>>
>>>>>>>>>> The recursive lock count for an object is not
>>>>>>>>>> correct, in cases, where a monitor is inflated after
>>>>>>>>>> recursive lightweight locks. In this case, the
>>>>>>>>>> recursion count is taken from the heavyweight
>>>>>>>>>> monitor, represented by the class ObjectMonitor.
>>>>>>>>>> ObjectMonitor::_recursions is the number of times
>>>>>>>>>> ObjectMonitor::enter() was called to acquire the lock
>>>>>>>>>> minus 1. This counter does not include the recursions
>>>>>>>>>> of lightweight locks, that happen before inflating
>>>>>>>>>> the monitor and is not equal to the recursion count
>>>>>>>>>> from a Java source level point of view.
>>>>>>>>>>
>>>>>>>>>> I added a test to the webrev to reproduce the
>>>>>>>>>> problem.
>>>>>>>>>>
>>>>>>>>>> The suggested fix is to call count_locked_objects,
>>>>>>>>>> even if there's a heavyweight monitor and get the
>>>>>>>>>> recursion count by iterating the vframes.
>>>>>>>>>>
>>>>>>>>>> Bug:
>>>>>>>>>>
>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8036666
>>>>>>>>>>
>>>>>>>>>> Webrev:
>>>>>>>>>>
>>>>>>>>>> http://cr.openjdk.java.net/~asiebenborn/8036666/webrev/
>>>>>>>>>> <http://cr.openjdk.java.net/%7Easiebenborn/8036666/webrev/><http://cr.openjdk.java.net/%7Easiebenborn/8036666/webrev/>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
> Thanks,
>>>>>>>>>>
>>>>>>>>>> Axel
>>
>>
> 

-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the source code.