Review Request: 8009298 and 8009777

[Coleen Phillimore]

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
>>>>
>>>
>>
>