Out Of Memory errors

OutOfMemory errors are usually reported by this kind of error dialog:

But this may not always be the case as displaying the error dialog needs a little memory. Java programs need to specify the maximum memory they can use. With a standard Sun JRE this setting must be set by command line (or in the BAT or SH file). To increase the memory limit used by JANIS the following option is set in the janis.bat file (or janis.sh for Linux):

start javaw -Djdbc.drivers=org.h2.Driver,com.mckoi.JDBCDriver -Xms100M -Xmx200M -jar Janis.jar

The option –Xmx200M specifies that JANIS will take at most 200Mbytes of memory. In case you have much more physical memory (e.g. 512Mbytes, 1GBytes,…) you can edit this command line and replace the option –Xmx200M with –Xmx400M or any other value. For example to allow JANIS to use at most 512Mbytes of memory the janis.bat file should be:

start javaw -Djdbc.drivers=org.h2.Driver,com.mckoi.JDBCDriver -Xms100M –Xmx512M -jar Janis.jar

You can check the maximum memory that JANIS can use in the About box:

The bottom part shows that:

The maximum memory that the Java virtual machine will use is set to ~200 MB, this is set at startup time
The Java virtual machine uses ~100 MB of memory
In these 100 MB, ~11 MB are free so JANIS uses ~89 MB (= 100 - 11)
If JANIS needs more than 100 MB, the Java virtual machine will grow up to 200 MB
But, if JANIS needs more than 200 MB, you will get an OutOfMemory error

You can also control the memory used by JANIS with the little tool found in Browser File menu:

This graph shows the current memory usage and the current limit which can grow up to the maximum value specified by the –Xmx option. The OutOfMemory situation occurs when the graph reaches the top.

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Last modified:Tuesday, 30-Nov-2010 19:02:22 CET