Review Request: 8009298 and 8009777

[Daniel D. Daugherty]

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
>>
>