RFR (S): 8023101 java/lang/management/MemoryMXBean/ResetPeakMemoryUsage.java fails

Staffan Larsen staffan.larsen at oracle.com
Fri Aug 16 00:00:26 PDT 2013


It maybe only happens with G1, but I don't think there is a guarantee that mbean.gc() will always cause all "freed" objects to be reclaimed. By allowing for the heap usage to be the same both before and after mbean.gc() I was hoping to make the test more stable.

But perhaps someone from the GC side can comment on what the guarantees are for mbean.gc() (which calls Runtime.gc() which calls JVM_GC() which does Universe::heap()->collect(GCCause::_java_lang_system_gc)) ? 

Thanks,
/Staffan

On 15 aug 2013, at 21:41, Mandy Chung <mandy.chung at oracle.com> wrote:

> Hi Staffan,
> 
> Is this issue specific to G1 such as mbean.gc() doesn't collect the "freed" obj?  The test wants to verify the peak usage won't change when GC frees up some space.
> 
> Mandy
> 
> On 8/15/2013 12:05 PM, Staffan Larsen wrote:
>> Please review this small update to the test. The fix allows for no change in heap usage to happen during a GC.
>> 
>> webrev: http://cr.openjdk.java.net/~sla/8023101/webrev.00/
>> bug: http://bugs.sun.com/view_bug.do?bug_id=8023101 (not available yet)
>> jbs: https://jbs.oracle.com/bugs/browse/JDK-8023101
>> 
>> Thanks,
>> /Staffan
> 



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