Startup Configuration

There are a number of startup settings that you can configure, including JAVA_HEAP_SIZE. Horizon startup scripts load ${OPENNMS_HOME}/etc/opennms.conf early in their startup, if that file exists.

No opennms.conf exists in the default RPM/DEB installation, but ${OPENNMS_HOME}/etc/examples includes a sample file that you can use as a starting point.

Table 1. Variables you may want to set
Variable Description Default Behavior

JAVA_HEAP_SIZE

Specifies the maximum amount of memory the JVM should use. You may want to increase this value if you experience long response times, frequent garbage collection that takes a lot of time, or see alarms that should have been cleared automatically still listed as alarms. See performance tuning on Discourse for more information.

2048

Units are in megabytes. Suffix m is added automatically with the result passed to JVM as an -Xmx flag.

JAVA_INITIAL_HEAP_SIZE

Specifies the initial amount of memory the JVM should use. Effectively sets a minimum memory value when used in conjunction with JAVA_HEAP_SIZE. You may want to increase this value if you experience long response times, frequent garbage collection that takes a lot of time, or see alarms that should have been cleared automatically still listed as alarms. It is good practice to set the JAVA_INITIAL_HEAP_SIZE and JAVA_HEAP_SIZE to the same value.

null

Units are in megabytes. Suffix m is added automatically with the result passed to JVM as an -Xms flag.

ADDITIONAL_MANAGER_OPTIONS

Additional options to pass to Java when starting Horizon.

Appended to other JVM startup flags.

MAXIMUM_FILE_DESCRIPTORS

You may want to change these values if you end up with too many "files open exceptions" in Horizon. See How to investigate file descriptor issues on Discourse for more information.

20480

Passed to ulimit -n before starting JVM.

MAXIMUM_SIZE_STACK_SEGMENT

Defines the size limit for each Java thread in the JVM.

8192

Units are in kilobytes. Passed to ulimit -s before starting JVM.