is it correct Heap Structure on basis of given JVM Parameters ?

[Jon Masamitsu]

Vipin,

If you want to see the heap after it has fully expanded, use -Xms2048m 
(not -Xms32m) and
-XX:NewSize=64m (not -XX:NewSize=8m) and add -XX:PrintGCDetails -version 
to your java
command line.  You'll see something like this

  $JAVA_HOME/bin/java  -XX:+PrintGCDetails -Xms2048m -XX:NewSize=64m 
-XX:NewRatio=2  -XX:MaxNewSize=64m -XX:SurvivorRatio=25  -Xmx2048m -version
java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) Server VM (build 21.0-b17, mixed mode)
Heap
  PSYoungGen      total 63168K, used 2432K [0xf7c00000, 0xfbc00000, 
0xfbc00000)
   eden space 60800K, 4% used [0xf7c00000,0xf7e600d0,0xfb760000)
   from space 2368K, 0% used [0xfb9b0000,0xfb9b0000,0xfbc00000)
   to   space 2368K, 0% used [0xfb760000,0xfb760000,0xfb9b0000)
  PSOldGen        total 2031616K, used 0K [0x7bc00000, 0xf7c00000, 
0xf7c00000)
   object space 2031616K, 0% used [0x7bc00000,0x7bc00000,0xf7c00000)
  PSPermGen       total 16384K, used 1356K [0x77c00000, 0x78c00000, 
0x7bc00000)
   object space 16384K, 8% used [0x77c00000,0x77d532d0,0x78c00000)

Jon


On 4/29/2014 2:54 AM, Sharma, Vipin K wrote:
>
> HI All
>
> In my Java application ( JDK 7) JVM parameters are
>
> -Xms32m -Xmx2048m -Xss1m -XX:+UseParallelGC -XX:NewRatio=2 
> -XX:NewSize=8m -XX:MaxNewSize=64m -XX:SurvivorRatio=25 
> -XX:+UseAdaptiveSizePolicy
>
> Xmx2048m                          : Maximum Heap memory is 2GB
>
> MaxNewSize=64m          :  Maximum Young Generation Size 64 MB
>
> NewRatio=2                       :  Old Generation Size will be double 
> of Young generation size so Maximum Old generation Size will be 64*2
>
> As per my understanding below will be Heap structure when all parts of 
> heap are allocated maximum memory
>
> Young(64 M )     + Old ( 128 M)    + Rest Memory only for Permanent 
> Generation Area
>
> I feel we are not using heap memory efficiently more than 1.8 GB is 
> allocated for Permanent Generation only.
>
> Is it correct understanding ? if not then what will be heap structure 
> in case we give max memory to all parts?
>
> Thanks,
>
> Vipin Sharma
>
>
>
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