Strage jmap heap output for G1 on 32bit JVM
jk at codearte.io
Wed May 20 20:46:10 UTC 2015
I've checked with latest JDK 9 and it's OK. However 8u60 still reports
incorrect number of regions for Xmx2g. For -Xmx2046m it's OK and for
-Xmx2047m there are 14336 regions reported and eden capacity is 15032385536
I don't know PrintHeapAtExit flag but I've added PrintHeapAtGC and it
garbage-first heap total 125952K, used 99580K [0x66600000, 0x667001ec,
region size 1024K, 62 young (63488K), 7 survivors (7168K)
Metaspace used 29856K, capacity 30136K, committed 30208K, reserved
2015-05-20 17:48 GMT+02:00 Jesper Wilhelmsson <jesper.wilhelmsson at oracle.com
> FYI, I filed JDK-8080784 to cover this issue.
> Jakub Kubryński skrev den 20/5/15 16:50:
>> Yes, I'll check it on latest Jdk9 and let you know.
>> 20 maj 2015 16:35 "Jesper Wilhelmsson" <jesper.wilhelmsson at oracle.com
>> <mailto:jesper.wilhelmsson at oracle.com>> napisał(a):
>> Ok. I tried that as well but it didn't reproduce.
>> After a closer look it seems as if it is the number of regions that
>> is wrong
>> and causes the huge free size reported. There have been a few changes
>> this area recently which may have fixed this issue.
>> Is it possible to try your reproducer with a recent build of JDK 9 or
>> latest version of 8u from the OpenJDK source repositories?
>> Jakub Kubryński skrev den 20/5/15 15:23:
>> 64 bit Linux with 32bit JVM.
>> 20 maj 2015 15:18 "Jesper Wilhelmsson" <
>> jesper.wilhelmsson at oracle.com
>> <mailto:jesper.wilhelmsson at oracle.com>
>> <mailto:jesper.wilhelmsson at oracle.com
>> <mailto:jesper.wilhelmsson at oracle.com>>> napisał(a):
>> Does this reproduce every time?
>> What platform is it?
>> I have tried to reproduce this on 32bit linux but can't see
>> anything weird
>> there. It seems likely that there is a variable with the
>> wrong type
>> somewhere on the way. I'll see if I can find something.
>> Jakub Kubryński skrev den 15/5/15 17:22:
>> I've just checked that on 32bit JVM (HotSpot 8u45) jmap
>> information for G1 collector. As you can see Xmx is set
>> to 2G
>> (which fits
>> MaxHeapSize) but regions count (almost 15k) and capacity
>> Any ideas
>> Heap Configuration:
>> MinHeapFreeRatio = 40
>> MaxHeapFreeRatio = 70
>> MaxHeapSize = 2147483648 <tel:
>> <tel:2147483648 <tel:2147483648>> (2048.0MB)
>> NewSize = 1048576 (1.0MB)
>> MaxNewSize = 428867584 (409.0MB)
>> OldSize = 4194304 (4.0MB)
>> NewRatio = 2
>> SurvivorRatio = 8
>> MetaspaceSize = 16777216 (16.0MB)
>> CompressedClassSpaceSize = 1073741824 (1024.0MB)
>> MaxMetaspaceSize = 4294963200
>> G1HeapRegionSize = 1048576 (1.0MB)
>> Heap Usage:
>> G1 Heap:
>> regions = 14336
>> capacity = 15032385536 <tel:15032385536> <tel:
>> <tel:15032385536>> (14336.0MB)
>> used = 76347888 (72.81101989746094MB)
>> free = 14956037648 (14263.188980102539MB)
>> 0.5078893687043872% used
>> Best regards,
>> Jakub Kubrynski
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