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

[Bengt Rutisson]

Hi Tony,

Looks good! Ship it!

Bengt

On 2012-01-12 19:32, 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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