Strage jmap heap output for G1 on 32bit JVM

Jesper Wilhelmsson jesper.wilhelmsson at oracle.com
Wed May 20 15:10:20 UTC 2015


Jakub,

Could you also try to run with -XX:+PrintHeapAtExit and send back the output?

Thanks,
/Jesper


Jakub Kubryński skrev den 20/5/15 16:50:
> Yes,  I'll check it on latest Jdk9 and let you know.
>
> Best,
> Jakub
>
> 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 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>
>         <mailto: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>
>         <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 (4095.99609375MB)
>                       G1HeapRegionSize         = 1048576 (1.0MB)
>
>                  Heap Usage:
>                  G1 Heap:
>                       regions  = 14336
>                       capacity = 15032385536 <tel:15032385536> <tel:15032385536
>         <tel:15032385536>> (14336.0MB)
>                       used     = 76347888 (72.81101989746094MB)
>                       free     = 14956037648 (14263.188980102539MB)
>                       0.5078893687043872% used
>
>                  --
>                  Best regards,
>                  Jakub Kubrynski
>


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