Increasing Java Applet Memory

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May 17, 2012

Increasing Java Applet Memory

Java applets are allocated a default heap size (typically 64 or 96 MB) by the operating system when they are loaded by a web browser. Some memory intensive applets, e.g., MOViewer, benefit from having more heap memory. In order to display multiple molecular orbitals, MOViewer should be allocated 256 MB of memory.

You can verify the amount of memory available to MOViewer by selecting Help -> About..., which will report both the free and total java memory.

Windows

Java 1.6 or higher supports dynamic allocation of memory when applet is invoked. WebMO requests 256 MB of RAM by use of the "PARAM NAME="java_arguments" value="-Xmx256m" when invoking the MOViewer applet. No further action is needed.

Earlier versions of java can have the default amount of memory changed through the Java Control Panel -> Java tab -> View... Add "-Xmx256m" as a runtime parameter.

Close all instances of your web browser for this change to take effect when the java applet is invoked.

Macintosh OS X

Mac OS X java does not currently support dynamic allocation of applet memory. Thus, the amount of memory for java applets must be changed using Applications -> Utilities -> Java Preferences.app. On the General tab, highlight the top Java Applet Plugin and click Options... Add "-Xmx256m" as an applet runtime parameter.
Close all instances of your web browser for this change to take effect when the java applet is invoked.

Linux/Unix