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wrapper.java.maxmemory Property

wrapper.java.maxmemory Property

Configuration Property Overview

- Configuration Property Overview
- JVM Configuration Properties
- Property List by Name

wrapper.java.maxmemory

The maximum amount of memory in megabytes that the JVM will be allowed to use. Defaults to 0, which will cause the JVM's default value to be used. For most JVMs, the default value is 64MB.

If a non-zero value is specified for this property then an appropriate `-Xmx` parameter will be added to the Java command generated by the Wrapper. If specified, the maximum memory must be greater than or equal to the value set for the wrapper.java.initmemory property.

If this property is set to 0 then it is also possible to specify the `-Xmx` parameter manually using the wrapper.java.additional.<n> property.

Example:

    wrapper.java.maxmemory=64

NOTE MEG

If an application is experiencing `java.lang.OutOfMemoryErrors` then this often indicates that the maximum amount of memory available to the application needs to be increased. Be aware that setting the maximum memory to a value which is greater than the amount of actual memory on the machine will result in memory swapping. Memory swapping is a function of the operating system, and thus its performance is highly operating system specific. However from experience this tends to result in a large decrease in application performance. In most cases, it is better to set the maximum memory to a value which fits within available memory and then rely on Java's garbage collection.

NOTE MEG

Unless you really do know everything there is to know about memory and Garbage Collection in Java, I would recommend reading through the following document. It describes in detail how the initial and maximum memory values affect Java performance and also goes into detail about what can be done to improve that performance for a given application.

- Tuning Garbage Collection with the 1.4.2 Java Virtual Machine.
- Tuning Garbage Collection with the 1.3.1 Java Virtual Machine.

by Leif Mortenson

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