Java Heap size

[Former Member]

Hi,

what is the meaning of Java heap size in XI server ?? In what way it is different from system RAM ?? On what basis we will select heap size ?? What is the importance of java heap size ??

Thanks

kumar

[Former Member · Accepted solution]

See <a href="https://service.sap.com/sap/support/notes/723909">OSS Note 723909</a>

<a href="https://service.sap.com/sap/support/notes/710146">OSS Note 710146</a>

[url=https://service.sap.com/sap/support/notes/764215]OSS Note 764215[/url]

[Former Member · Accepted solution]

could you plz explain me in simple words .......as you know ??

thanks

kumar

[Former Member · Accepted solution]

Hi,

The Java heap is where the objects of a Java program live. It is a repository for live objects, dead objects, and free memory. When an object can no longer be reached from any pointer in the running program, it is considered "garbage" and ready for collection.

The JVM heap size determines how often and how long the VM spends collecting garbage. If you set a large heap size, full garbage collection is slower, but it occurs less frequently. If you set your heap size in accordance with your memory needs, full garbage collection is faster, but occurs more frequently.

-Xms<size> initial Java heap size

-Xmx<size> maximum Java heap size

These parameters which are defined in Configtool determine how much Java heap can be used of the Total RAM.

The max Java heap size should be with in the RAM so that it does not under go Paging.

Award points if helpful.

Thanks,

Tanuj

[Former Member]

Also For importance of Java Heap size please go through this blog

<b>/people/sap.user72/blog/2006/01/09/what-stops-you-from-a-successful-installation-of-java-system

Thanks

Abhishek

[Former Member]

Java heap is the heap size allocated to JVM applications which takes care of the new objects being created. If the objects being created exceed the heap size, it will throw an error saying memoryOutof Bound

Or u can say

The heap is the runtime data area from which memory for all class instances and arrays is allocated. The heap may be of a fixed size or may be expanded. The heap is created on virtual machine start-up. If you have complicated algorithms or big caching which might create lot of objects in memory you may need bigger heap size

Java Heap vs RAM

Please go through following forum. This might help:

<b>http://www.velocityreviews.com/forums/t128137-java-heap-vs-os-memory.html</b>

<b>

/thread/40047 [original link is broken]

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