RFR(S): 8061443: Whitebox get*VMFlag() methods fail with develop flags in product builds

[Staffan Larsen]

On 23 okt 2014, at 04:35, David Holmes <david.holmes at oracle.com> wrote:

> On 23/10/2014 7:22 AM, Vladimir Kozlov wrote:
>> getVMOption() specification does not say anything about product, locked
>> or develop flags. "If a VM option of the given name does not exist" can
>> interpreted different ways.
> 
> Perhaps, but conceptually develop flags are not part of a product build and by definition non-product flags are not part of a product build, so I think the existing jmm code is quite right to exclude them and the new code should do the same. It doesn't make sense to me to present someone with a list of flags that can't actually be used.

I agree with David here. Instead of changing the JMM API, you can add functionality to the WhiteBox API to get the value of non-product flags.

/Staffan

> 
> Thanks,
> David
> 
>> http://docs.oracle.com/javase/8/docs/jre/api/management/extension/com/sun/management/HotSpotDiagnosticMXBean.html
>> 
>> 
>> VMOption getVMOption(String name)
>> 
>>     Returns a VMOption object for a VM option of the given name.
>> 
>>     Returns:
>>         a VMOption object for a VM option of the given name.
>>     Throws:
>>         NullPointerException - if name is null.
>>         IllegalArgumentException - if a VM option of the given name
>> does not exist.
>> 
>> Thanks,
>> Vladimir
>> 
>> On 10/22/14 6:46 AM, Tobias Hartmann wrote:
>>> Hi David,
>>> 
>>> On 22.10.2014 14:33, David Holmes wrote:
>>>> On 22/10/2014 6:48 PM, Tobias Hartmann wrote:
>>>>> Hi David,
>>>>> 
>>>>> On 22.10.2014 04:16, David Holmes wrote:
>>>>>> Hi Tobias,
>>>>>> 
>>>>>> On 21/10/2014 11:08 PM, Tobias Hartmann wrote:
>>>>>>> Hi,
>>>>>>> 
>>>>>>> please review the following patch.
>>>>>>> 
>>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8061443
>>>>>>> Webrev: http://cr.openjdk.java.net/~thartmann/8061443/webrev.00/
>>>>>>> 
>>>>>>> Problem:
>>>>>>> The Whitebox API methods get*VMFlag() fail with develop/notproduct
>>>>>>> flags in
>>>>>>> product builds.
>>>>>>> 
>>>>>>> Solution:
>>>>>>> The code is changed to invoke 'Flag::find_flag' with
>>>>>>> allow_locked=true and
>>>>>>> return_flag=true to return both locked and notproduct/develop
>>>>>>> flags. I also
>>>>>>> changed the JVM monitoring and management code 'jmm_GetVMGlobals()'.
>>>>>> 
>>>>>> Why did you change the jmm code? You seemed to have changed its
>>>>>> semantics -
>>>>>> which may require a CCC request.
>>>>> 
>>>>> I changed the jmm code because the whitebox tests use a JMM call to
>>>>> verify the
>>>>> return value (see 'VmFlagTest<T>.getVMOptionAsString()').
>>>>> 
>>>>> Do you think a CCC request is necessary here?
>>>> 
>>>> Depends what the jmm code is supposed to return - I don't know the
>>>> spec. But
>>>> changing the behaviour for the sake of a test without consideration
>>>> of real
>>>> users is not something that should be done lightly.
>>> 
>>> I agree. I filed a CCC request and attached the link to the bug.
>>> 
>>> Thanks,
>>> Tobias
>>> 
>>>> 
>>>> David
>>>> 
>>>>> Thanks,
>>>>> Tobias
>>>>> 
>>>>>> 
>>>>>> Thanks,
>>>>>> David
>>>>>> 
>>>>>>> I adapted the existing tests to check for develop flags as well. I
>>>>>>> noticed that
>>>>>>> HotspotDiagnosticMXBean.getVMOption() fails with double flags and
>>>>>>> filed
>>>>>>> JDK-8061616 [1].
>>>>>>> 
>>>>>>> Testing:
>>>>>>> - New testcases
>>>>>>> - JPRT
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> Tobias
>>>>>>> 
>>>>>>> 
>>>>>>> [1] https://bugs.openjdk.java.net/browse/JDK-8061616
>>>>>>>