Review Request: 8009298 and 8009777

[Zhengyu Gu]

Thanks,

-Zhengyu

On 3/19/2013 5:11 PM, Coleen Phillimore wrote:
>
> Good.
> Coleen
>
> On 3/19/2013 4:45 PM, Zhengyu Gu wrote:
>> Updated webrev based on Coleen and Dan's comment.
>>
>> http://cr.openjdk.java.net/~zgu/8009298/webrev.01/
>>
>>
>> Thanks,
>>
>> -Zhengyu
>>
>> On 3/19/2013 11:23 AM, Daniel D. Daugherty wrote:
>>> The 2nd -> 4th lines will need a space before the final double-quote
>>> to print properly.
>>>
>>> Dan
>>>
>>>
>>> On 3/19/13 8:57 AM, Coleen Phillmore wrote:
>>>>
>>>> Zhengyu,
>>>> This looks good.   NIce documentation for the flag in globals.hpp. 
>>>> Can you reword slightly:
>>>>
>>>> +           "Automatically shutdown native memory tracking in 
>>>> stress "        \
>>>> +           "situations. When it is set to false, native memory 
>>>> tracking"      \
>>>> +           "will try its best to stay alive, even if it means that 
>>>> it has to" \
>>>> +           "sacrifice JVM 
>>>> performance")                                      \
>>>>
>>>>
>>>> Coleen
>>>>
>>>> On 3/11/2013 2:21 PM, Zhengyu Gu wrote:
>>>>> 8009298: NMT: Special version of class loading/unloading with 
>>>>> runThese stresses out NMT 
>>>>> <https://jbs.oracle.com/bugs/browse/JDK-8009298>
>>>>> 8009777: NMT: add new NMT dcmd to control auto shutdown option 
>>>>> <https://jbs.oracle.com/bugs/browse/JDK-8009777>
>>>>>
>>>>> The two are related. The change is to add an addition VM 
>>>>> diagnostic command-line option "AutoShutdownNMT".
>>>>>
>>>>> By default, native memory tracking runtime shuts itself down under 
>>>>> stress situation, and release memory to allow JVM continue 
>>>>> running. But this feature can be undesirable when this is the 
>>>>> situation we really want to know what's happening to JVM memory 
>>>>> usage, even that means that we need to sacrifice JVM performance.
>>>>>
>>>>> When AutoShutdownNMT is set to false, NMT will try its best to 
>>>>> stay alive by slowing down threads calling memory 
>>>>> allocation/de-allocation.
>>>>>
>>>>> Webrev: http://cr.openjdk.java.net/~zgu/8009298/webrev.00/
>>>>>
>>>>> Tests:
>>>>> The test case is special version of runThese, it uses 12 threads 
>>>>> to load/unloading classes without executing any tests.
>>>>>
>>>>> Following two memory usage graphs show the different behavior with 
>>>>> AutoShutdownNMT on/off.
>>>>>
>>>>> AutoShutdownNMT = true
>>>>> http://cr.openjdk.java.net/~zgu/8009298/webrev.00/autoShutdown.png
>>>>>   The steep drop in memory usage was result of shutting down of 
>>>>> native memory tracking.
>>>>>
>>>>> AutoShutdownNMT = false
>>>>> http://cr.openjdk.java.net/~zgu/8009298/webrev.00/noAutoShutdown.png
>>>>>    The steep dig was result of class unloading.
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> -Zhengyu
>>>>>
>>>>
>>>
>>
>