1.8GB Heap Limit in ColdFusion MX
Macromedia's Recent Technote: Maximum JVM heap size greater than 1.8GB will prevent ColdFusion MX from starting points out the limitations of a the JVM on a 32 bit architecture.
Wondering where the number 1.8GB comes from? Moazam Raja's recent blog entry (link no longer works: http://www.unixville.com/~moazam/categories/jvmInternals/) explains. 32 bit processes can only address 4GB of memory, windows reserves 2GB for the kernel. So where's the other .2 GB? It is allocated to the the JVM's
permanent generation (this stores meta data for the JVM). Many people increase the size of the permanent generation (for CFM or JSP apps) using the jvm startup option
-XX:MaxPermSize. If you increase the perm generation (and you may want to) keep in mind your Max heap size will be less than 1.8GB.
Of course if you have these problems you should consider upgrading to a 64 bit architecture which have much larger limits.
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1.8GB Heap Limit in ColdFusion MX was first published on June 08, 2004.
If you like reading about jvm, heap, or cf then you might also like:
- ColdFusion Memory Usage Stats
- Getting Size of Heap and Non Heap Memory in CFML
- Robi Sen on Hung Servers, java.lang.OutOfMemory errors and Tuning CF JVM
- Server Memory Flash Remoting Tool
- ColdFusion Garbage
- Have you tuned your JVM on ColdFusion MX yet?
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