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Hi all,<br>
<br>
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):<br>
<br>
<a class="moz-txt-link-freetext" href="http://cr.openjdk.java.net/~tonyp/7097586/webrev.0/">http://cr.openjdk.java.net/~tonyp/7097586/webrev.0/</a><br>
<br>
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.<br>
<br>
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).<br>
<br>
Tony<br>
<br>
BEFORE:<br>
<br>
<tt>using thread-local object allocation.<br>
Garbage-First (G1) GC with 8 thread(s)<br>
<br>
Heap Configuration:<br>
MinHeapFreeRatio = 40<br>
MaxHeapFreeRatio = 70<br>
MaxHeapSize = 1073741824 (1024.0MB)<br>
NewSize = 1048576 (1.0MB)<br>
MaxNewSize = 4294967295 (4095.9999990463257MB)<br>
OldSize = 4194304 (4.0MB)<br>
NewRatio = 2<br>
SurvivorRatio = 8<br>
PermSize = 16777216 (16.0MB)<br>
MaxPermSize = 67108864 (64.0MB)<br>
<br>
Heap Usage:<br>
G1 Young Generation<br>
Eden Space:<br>
capacity = 19922944 (19.0MB)<br>
used = 3145728 (3.0MB)<br>
free = 16777216 (16.0MB)<br>
15.789473684210526% used<br>
From Space:<br>
capacity = 2097152 (2.0MB)<br>
used = 2097152 (2.0MB)<br>
free = 0 (0.0MB)<br>
100.0% used<br>
To Space:<br>
capacity = 0 (0.0MB)<br>
used = 0 (0.0MB)<br>
free = 0 (0.0MB)<br>
0.0% used<br>
G1 Old Generation<br>
capacity = 19922944 (19.0MB)<br>
used = 5849192 (5.578224182128906MB)<br>
free = 14073752 (13.421775817871094MB)<br>
29.359074642783717% used<br>
Perm Generation:<br>
capacity = 16777216 (16.0MB)<br>
used = 2749208 (2.6218490600585938MB)<br>
free = 14028008 (13.378150939941406MB)<br>
16.38655662536621% used<br>
<br>
1719 interned Strings occupying 137520 bytes.<br>
</tt><br>
<br>
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):<br>
<br>
<tt>using thread-local object allocation.<br>
Garbage-First (G1) GC with 8 thread(s)<br>
<br>
Heap Configuration:<br>
MinHeapFreeRatio = 40<br>
MaxHeapFreeRatio = 70<br>
MaxHeapSize = 67108864 (64.0MB)<br>
NewSize = 1048576 (1.0MB)<br>
MaxNewSize = 4294967295 (4095.9999990463257MB)<br>
OldSize = 4194304 (4.0MB)<br>
NewRatio = 2<br>
SurvivorRatio = 8<br>
PermSize = 16777216 (16.0MB)<br>
MaxPermSize = 67108864 (64.0MB)<br>
<b> G1HeapRegionSize = 1048576 (1.0MB)<br>
</b><br>
Heap Usage:<br>
<b>G1 Heap:<br>
regions = 57<br>
capacity = 59768832 (57.0MB)<br>
used = 18018304 (17.18359375MB)<br>
free = 41750528 (39.81640625MB)<br>
30.146655701754387% used<br>
</b>G1 Young Generation:<br>
Eden Space:<br>
<b> regions = 3<br>
</b> capacity = 30408704 (29.0MB)<br>
used = 3145728 (3.0MB)<br>
free = 27262976 (26.0MB)<br>
10.344827586206897% used<br>
<b>Survivor Space:<br>
regions = 2<br>
</b> capacity = 2097152 (2.0MB)<br>
used = 2097152 (2.0MB)<br>
free = 0 (0.0MB)<br>
100.0% used<br>
G1 Old Generation:<br>
<b> regions = 13<br>
</b> capacity = 27262976 (26.0MB)<br>
used = 12775424 (12.18359375MB)<br>
free = 14487552 (13.81640625MB)<br>
46.85997596153846% used<br>
Perm Generation:<br>
capacity = 16777216 (16.0MB)<br>
used = 2741840 (2.6148223876953125MB)<br>
free = 14035376 (13.385177612304688MB)<br>
16.342639923095703% used<br>
<br>
1710 interned Strings occupying 136904 bytes.</tt><br>
<br>
<br>
<br>
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