Review request(7u): JDK-8010738: G1: Output for full GCs with +PrintGCDetails should contain perm gen/meta data size change info

Poonam Bajaj poonam.bajaj at oracle.com
Fri Apr 18 01:53:20 UTC 2014


Hi Jon,

On 4/17/2014 10:07 PM, Jon Masamitsu wrote:
> Poonam,
>
> In jdk7 I think there is a
>
>  GenCollectedHeap::print_perm_heap_change()
>
> Your changes have added in G1CollectorPolicy
> 1168 void G1CollectorPolicy::print_perm_heap_change(size_t perm_prev_used) const {
>
>
> Is there still a  GenCollectedHeap::print_perm_heap_change() in the jdk7
> you're fixing and could you have used that instead of adding the
> print_perm_heap_change() to G1CollectorPolicy.

Yes, there is print_perm_heap_change() in GenCollectedHeap class. But 
according to the following hierarchy of classes, I could not use it in 
G1CollectedHeap

//
// CollectedHeap
//   SharedHeap
//       GenCollectedHeap
//       G1CollectedHeap
//   ParallelScavengeHeap
//

So I added the similar function in G1CollectorPolicy. I can move it to 
G1CollectedHeap too. And if we don't want duplication, I can explore the 
possibility of moving it to SharedHeap and then use it in both the 
derived classes.

Thanks,
Poonam

>
>
> Jon
>
>
>
> On 4/16/2014 6:03 PM, Poonam Bajaj wrote:
>> Hi,
>>
>> Could I have reviews for the following fix:
>>
>> JDK-8010738 <https://bugs.openjdk.java.net/browse/JDK-8010738>: G1: 
>> Output for full GCs with +PrintGCDetails should contain perm gen/meta 
>> data size change info
>> webrev: http://cr.openjdk.java.net/~poonam/8010738/webrev.00/
>>
>> With JDK7 G1GC when we use -XX:+PrintGCDetails option, PermGen 
>> information does not get printed in the Full GC logs as shown below:
>> [Full GC 16M->16M(20M), 0.7055536 secs]
>>    [Eden: 0.0B(1024.0K)->0.0B(1024.0K) Survivors: 0.0B->0.0B Heap: 
>> 16.7M(20.0M)->16.7M(20.0M)]
>>
>> PermGen info should also get printed with Full GC info similar to 
>> what other garbage collectors report. These changes are backport of 
>> the fix in jdk8 where MetaSpace info gets printed in the Full GC logs.
>>
>> With the fix the output looks like:
>> [Full GC 16M->16M(20M), 0.6763478 secs]
>>    [Eden: 0.0B(1024.0K)->0.0B(1024.0K) Survivors: 0.0B->0.0B Heap: 
>> 16.7M(20.0M)->16.7M(20.0M)], [Perm: 1725K->1725K(16384K)]
>>
>>
>> Thanks,
>> Poonam
>>
>
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