Weblogic JDK 1.6 Error Could not reserve enough space for object heap

Weblogic 10 running on HP-UX throws this error on startup when we try to give 3 GB Xms and Xmx.

-Dweblogic.system.BootIdentityFile=/portalapp/bea/user_projects/domains/MSD4/servers/MS4/data/nodemanager/boot.properties -Dweblogic.nodemanager.ServiceEnabled=true -Dweblogic.security.SSL.ignoreHostnameVerification=false -Dweblogic.ReverseDNSAllowed=false -server -Xms3g -Xmx3g -Xmn1024m -XX:+AggressiveHeap -XX:+UseParallelGC -XX:ParallelGCThreads=20 -XX:PermSize=1024m -XX:MaxPermSize=1024m -XX:MaxTenuringThreshold=3 -XX:LargePageSizeInBytes=4m -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:SurvivorRatio=8 -XX:-UseAdaptiveSizePolicy -Xloggc:/portal_logs/gclog/MS4_gclog.log weblogic.Server >

<Feb 17, 2010 10:56:06 AM> <Info> <NodeManager> <Working directory is "/portalapp/bea/user_projects/domains/MSD4">

<Feb 17, 2010 10:56:06 AM> <Info> <NodeManager> <Server output log file is "/portalapp/bea/user_projects/domains/MSD4/servers/MS4/logs/MS4.out">
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
<Feb 17, 2010 10:56:06 AM> <Debug> <NodeManager> <Waiting for the process to die: 13663>
<Feb 17, 2010 10:56:06 AM> <Info> <NodeManager> <Server failed during startup so will not be restarted>

Additional information:

os.name = HP-UX
os.version = B.11.31

java.version = 1.6.0.04
java.vm.info = mixed mode
java.vm.name = Java HotSpot(TM) Server VM
java.vm.specification.name = Java Virtual Machine Specification
java.vm.specification.vendor = Sun Microsystems Inc.
java.vm.specification.version = 1.0
java.vm.vendor = "Hewlett-Packard Company"
java.vm.version = 11.3-b02-jre1.6.0.04-rc2
java.runtime.version = 1.6.0.04-jinteg_28_apr_2009_04_46-b00


Analysis:


Though we are using a 64-bit server which has 16 GB RAM, we are unable to assign more than 2 Gb to the Weblogic heap.

This value in the startup log shows that the JVM is a 32-bit one.

sun.arch.data.model = 32


In a 32-bit JVM – the process cannot address memory higher than 4 GB in all. But as per Sun site, in reality we cannot get more than 2G.

As per this URL: http://java.sun.com/docs/hotspot/HotSpotFAQ.html#gc_heap_32bit

Why can't I get a larger heap with the 32-bit JVM?

The maximum theoretical heap limit for the 32-bit JVM is 4G. Due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead, in practice the limit can be much lower. On most modern 32-bit Windows systems the maximum heap size will range from 1.4G to 1.6G. On 32-bit Solaris kernels the address space is limited to 2G.

So we tuned the heap to 2 GB for now. i.e. set Xmx and Xms to 2G and that solved it.