Strage jmap heap output for G1 on 32bit JVM

Jesper Wilhelmsson jesper.wilhelmsson at oracle.com
Wed May 20 14:35:02 UTC 2015


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 in this area 
recently which may have fixed this issue.

Is it possible to try your reproducer with a recent build of JDK 9 or the latest 
version of 8u from the OpenJDK source repositories?
/Jesper


Jakub Kubryński skrev den 20/5/15 15:23:
> 64 bit Linux with 32bit JVM.
>
> Cheers,
> Jakub
>
> 20 maj 2015 15:18 "Jesper Wilhelmsson" <jesper.wilhelmsson at oracle.com
> <mailto:jesper.wilhelmsson at oracle.com>> napisał(a):
>
>     Hi,
>
>     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.
>     /Jesper
>
>
>     Jakub Kubryński skrev den 15/5/15 17:22:
>
>         Hi,
>
>         I've just checked that on 32bit JVM (HotSpot 8u45) jmap reports strange
>         region
>         information for G1 collector. As you can see Xmx is set to 2G (which fits
>         MaxHeapSize) but regions count (almost 15k) and capacity is incorrect.
>         Any ideas
>         why?
>
>         Heap Configuration:
>              MinHeapFreeRatio         = 40
>              MaxHeapFreeRatio         = 70
>              MaxHeapSize              = 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 (4095.99609375MB)
>              G1HeapRegionSize         = 1048576 (1.0MB)
>
>         Heap Usage:
>         G1 Heap:
>              regions  = 14336
>              capacity = 15032385536 <tel:15032385536> (14336.0MB)
>              used     = 76347888 (72.81101989746094MB)
>              free     = 14956037648 (14263.188980102539MB)
>              0.5078893687043872% used
>
>         --
>         Best regards,
>         Jakub Kubrynski
>


More information about the hotspot-gc-dev mailing list