Chapter 4. Configuring your JBoss EAP server and application

JAVA_OPTS

-verbose:class

No default

Multiple

JVM options to pass to the java command.

Use JAVA_OPTS_APPEND to configure additional JVM settings. If you use JAVA_OPTS, some unconfigurable defaults are not added to the server JVM settings. You must explicitly add these settings.

Using JAVA_OPTS disables certain settings added by default by the container scripts. Disabled settings include:

In addition, if automatic memory calculation is not enabled, the inital Java memory (-Xms) and maximum Java memory (-Xmx) are not defined.

Add these defaults if you use JAVA_OPTS to configure additional settings.

JAVA_OPTS_APPEND

-Dsome.property=value

No default

Multiple

User-specified Java options to append to generated options in JAVA_OPTS.

JAVA_MAX_MEM_RATIO

50

80

-Xmx

Use this variable when the -Xmx option is not specified in JAVA_OPTS. The value of this variable is used to calculate the default maximum heap memory size based on the restrictions of the container. If this variable is used in a container without a memory constraint, the variable has no effect. If this variable is used in a container that does have a memory constraint, the value of -Xmx is set to the specified ratio of the container’s available memory. The default value, 50 means that 50% of the available memory is used as an upper boundary. To skip calculation of maximum memory, set the value of this variable to 0. No -Xmx option will be added to JAVA_OPTS.

JAVA_INITIAL_MEM_RATIO

25

-Xms

-Xms

Use this variable when the -Xms option is not specified in JAVA_OPTS. The value of this variable is used to calculate the default initial heap memory size based on the maximum heap memory. If this variable is used in a container without a memory constraint, the variable has no effect. If this variable is used in a container that does have a memory constraint, the value of -Xms is set to the specified ratio of the -Xmx memory. The default value, 25 means that 25% of the maximum memory is used as the initial heap size. To skip calculation of initial memory, set the value of this variable to 0. No -Xms option will be added to JAVA_OPTS.

JAVA_MAX_INITIAL_MEM

4096

4096

-Xms

JAVA_MAX_INITIAL_MEM environment variable is now deprecated, use JAVA_OPTS to provide -Xms option. For example, JAVA_OPTS=-Xms256m

JAVA_DIAGNOSTICS

true

false (disabled)

-Xlog:gc:utctime -XX:NativeMemoryTracking=summary

Set the value of this variable to true to include diagnostic information in standard output when events occur. If this variable is defined as true in an environment where JAVA_DIAGNOSTICS has already been defined as true, diagnostics are still included.

DEBUG

true

false

-agentlib:jdwp=transport=dt_socket,address=$DEBUG_PORT,server=y,suspend=n

Enables remote debugging.

DEBUG_PORT

8787

8787

-agentlib:jdwp=transport=dt_socket,address=$DEBUG_PORT,server=y,suspend=n

Specifies the port used for debugging.

GC_MIN_HEAP_FREE_RATIO

20

10

-XX:MinHeapFreeRatio

Minimum percentage of heap free after garbage collection to avoid expansion.

GC_MAX_HEAP_FREE_RATIO

40

20

-XX:MaxHeapFreeRatio

Maximum percentage of heap free after garbage collection to avoid shrinking.

GC_TIME_RATIO

4

4

-XX:GCTimeRatio

Specifies the ratio of the time spent outside of garbage collection (for example, time spent in application execution) to the time spent in garbage collection.

GC_ADAPTIVE_SIZE_POLICY_WEIGHT

90

90

-XX:AdaptiveSizePolicyWeight

The weighting given to the current garbage collection time versus the previous garbage collection times.

GC_METASPACE_SIZE

20

96

-XX:MetaspaceSize

The initial metaspace size.

GC_MAX_METASPACE_SIZE

100

No default

-XX:MaxMetaspaceSize

The maximum metaspace size.

GC_CONTAINER_OPTIONS

-XX:+UserG1GC

-XX:-UseParallelGC

-XX:-UseParallelGC

Specifies the Java garbage collection to use. The value of the variable is specified by using the Java Runtime Environment (JRE) command-line options. The specified JRE command overrides the default.