Edge Documentation

This page details some settings that the AppBoard system administrator can modify to allocate the proper amount of server memory to AppBoard.

Allocating Additional Memory

If your system is experiencing lags or performance issues, or you see the error message "Out of heap space", you may want to allocate additional memory to the Java Virtual Machine.

The heap size is the amount of Java object storage memory the Java Virtual Machine (JVM) is allowed to allocate. In the case of most JVMs, the default setting of the maximum heap size is 64MB. You can increase the maximum heap size of applications by setting the -Xmx JVM parameter. For example -Xmx1024m allows maximum 1GB (1024MB) heap to be allocated for the JVM. It is recommended to specify a considerably lower value than the total amount of physical RAM on the server, so the operating system and other applications will also have enough space. Otherwise, the swap memory of the operating system will be used, which can result in high disk activity, and reduced system performance.

Perform the following steps to review the memory heap size settings for AppBoard:

1. Go to [AppBoard_Home]/server/bin/setenv.bat (or setenv.sh on Unix).
2. Open the file in a text editor. You will see lines similar to the following:

[xml,N]set JAVA_OPTS=%JAVA_OPTS% -Xmx1536m -Xms256m rem set JAVA_OPTS=%JAVA_OPTS% -Xmx2048m -Xms256m

The limit for 32-bit operating systems is less than the 4096 MB of theoretical address space. For Windows, the real limit is under 1600 MB (due to memory used for non-heap storage and Windows limitation of user space addressable memory to under 2048 MB), which is why the default is 1536 MB (512 MB x 3). If AppBoard is running on both a 64-bit operating system and a 64-bit Java, it can support a higher setting for the heap size. For example, you can increase the memory available to Tomcat from 1536 MB to 2048 MB by activating the second setting, as follows:

[xml,N]rem set JAVA_OPTS=%JAVA_OPTS% -Xmx1536m -Xms256m set JAVA_OPTS=%JAVA_OPTS% -Xmx2048m -Xms256m

Depending on the RAM on your AppBoard server, higher values for the maximum heap space will typically provide better performance overall. However, for complete system optimization, the efficiency of your system with regard to data retrieval, caching, querying, etc., must be considered and will often be the limiting factors for performance.

Monitoring Garbage Collection

If you are experiencing a memory leak, and would like to carefully report on each garbage collection event, you can log this data to a file by using the -Xloggc:file Java Option. Each reported event will be preceeded by the time (in seconds) since the first garbage-collection event.

Always use a local file system for storage of this file to avoid stalling the JVM due to network latency.

Perform the following steps to enable memory logging for AppBoard to a file:

1. Go to [AppBoard_Home]/server/bin/setenv.bat (or setenv.sh on Unix).
2. Open the file in a text editor. You will see a line similar to the following:

   [xml,N]set JAVA_OPTS=%JAVA_OPTS% -Xmx2048m -Xms256m

3. Add the Xlogcc parameter, such as in the following example:

   [xml,N]set JAVA_OPTS=%JAVA_OPTS% -Xmx2048m -Xms256m -Xloggc:c:\GCout.txt