CRR (S): 7097586: G1: improve the per-space output when using jmap -heap

[Tony Printezis]

Thanks John!

On 01/17/2012 04:58 PM, John Cuthbertson wrote:
> Hi Tony,
>
> This looks good to me.
>
> JohnC
>
> On 01/12/12 10:32, Tony Printezis wrote:
>> Hi all,
>>
>> I'd like a couple of code reviews for this change that enhances the 
>> heap summary information generated by the SA (which is used for the 
>> jmap -heap output):
>>
>> http://cr.openjdk.java.net/~tonyp/7097586/webrev.0/
>>
>> Currently, the heap summary generated for G1 is as close as possible 
>> to what's generated for the other GCs. Bengt made a good suggestion 
>> that it'd be helpful to enhance the output with some G1-specific 
>> information in order to make it more informative. The important 
>> changes are the 15 lines or so that were changed in HeapSummary.java, 
>> the rest is boilerplate to be able to access specific fields and 
>> objects from the SA. I included before / after jmap -heap output below.
>>
>> Note that we actually had a small bug in the code which caused the 
>> sizing information in the G1MonitoringSupport object to become 
>> inconsistent between a cleanup and the subsequent GC: the old space 
>> information was not updated to reflect any old region reclamation 
>> during cleanup. I fixed this as part of this change too (I'll add a 
>> note to the CR).
>>
>> Tony
>>
>> BEFORE:
>>
>> using thread-local object allocation.
>> Garbage-First (G1) GC with 8 thread(s)
>>
>> Heap Configuration:
>>    MinHeapFreeRatio = 40
>>    MaxHeapFreeRatio = 70
>>    MaxHeapSize      = 1073741824 (1024.0MB)
>>    NewSize          = 1048576 (1.0MB)
>>    MaxNewSize       = 4294967295 (4095.9999990463257MB)
>>    OldSize          = 4194304 (4.0MB)
>>    NewRatio         = 2
>>    SurvivorRatio    = 8
>>    PermSize         = 16777216 (16.0MB)
>>    MaxPermSize      = 67108864 (64.0MB)
>>
>> Heap Usage:
>> G1 Young Generation
>> Eden Space:
>>    capacity = 19922944 (19.0MB)
>>    used     = 3145728 (3.0MB)
>>    free     = 16777216 (16.0MB)
>>    15.789473684210526% used
>> >From Space:
>>    capacity = 2097152 (2.0MB)
>>    used     = 2097152 (2.0MB)
>>    free     = 0 (0.0MB)
>>    100.0% used
>> To Space:
>>    capacity = 0 (0.0MB)
>>    used     = 0 (0.0MB)
>>    free     = 0 (0.0MB)
>>    0.0% used
>> G1 Old Generation
>>    capacity = 19922944 (19.0MB)
>>    used     = 5849192 (5.578224182128906MB)
>>    free     = 14073752 (13.421775817871094MB)
>>    29.359074642783717% used
>> Perm Generation:
>>    capacity = 16777216 (16.0MB)
>>    used     = 2749208 (2.6218490600585938MB)
>>    free     = 14028008 (13.378150939941406MB)
>>    16.38655662536621% used
>>
>> 1719 interned Strings occupying 137520 bytes.
>>
>>
>> AFTER (I marked the changes with bold; note that now there's only one 
>> Survivor section, as G1 does not have the concept of two survivors 
>> that are always allocated):
>>
>> using thread-local object allocation.
>> Garbage-First (G1) GC with 8 thread(s)
>>
>> Heap Configuration:
>>    MinHeapFreeRatio = 40
>>    MaxHeapFreeRatio = 70
>>    MaxHeapSize      = 67108864 (64.0MB)
>>    NewSize          = 1048576 (1.0MB)
>>    MaxNewSize       = 4294967295 (4095.9999990463257MB)
>>    OldSize          = 4194304 (4.0MB)
>>    NewRatio         = 2
>>    SurvivorRatio    = 8
>>    PermSize         = 16777216 (16.0MB)
>>    MaxPermSize      = 67108864 (64.0MB)
>> *   G1HeapRegionSize = 1048576 (1.0MB)
>> *
>> Heap Usage:
>> *G1 Heap:
>>    regions  = 57
>>    capacity = 59768832 (57.0MB)
>>    used     = 18018304 (17.18359375MB)
>>    free     = 41750528 (39.81640625MB)
>>    30.146655701754387% used
>> *G1 Young Generation:
>> Eden Space:
>> *   regions  = 3
>> *   capacity = 30408704 (29.0MB)
>>    used     = 3145728 (3.0MB)
>>    free     = 27262976 (26.0MB)
>>    10.344827586206897% used
>> *Survivor Space:
>>    regions  = 2
>> *   capacity = 2097152 (2.0MB)
>>    used     = 2097152 (2.0MB)
>>    free     = 0 (0.0MB)
>>    100.0% used
>> G1 Old Generation:
>> *   regions  = 13
>> *   capacity = 27262976 (26.0MB)
>>    used     = 12775424 (12.18359375MB)
>>    free     = 14487552 (13.81640625MB)
>>    46.85997596153846% used
>> Perm Generation:
>>    capacity = 16777216 (16.0MB)
>>    used     = 2741840 (2.6148223876953125MB)
>>    free     = 14035376 (13.385177612304688MB)
>>    16.342639923095703% used
>>
>> 1710 interned Strings occupying 136904 bytes.
>>
>>
>>
>
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