Chapter 8. Configuring JVM settings
You can configure Java Virtual Machine (JVM) settings for a standalone JBoss EAP server, or a JBoss EAP server in a managed domain.
For a standalone JBoss EAP server instance, the server startup processes pass JVM settings to the JBoss EAP server at startup. These can be declared from the command line before launching JBoss EAP, or using the System Properties page under Configuration in the management console.
In a managed domain, JVM settings are declared in the host.xml
and domain.xml
configuration files, and can be configured at host, server group, or server levels.
Configure system properties in JAVA_OPTS
if they need to be read by the JVM itself, or JBoss EAP modules (such as the logging manager), during the initial phase of startup of a standalone server, or a managed domain host controller.
8.1. Configuring JVM settings for a standalone server
You can define the Java Virtual Machine (JVM) settings for standalone JBoss EAP server instances at runtime by setting the JAVA_OPTS
environment variable before starting the server. Alternatively, you can add the JVM settings to the standalone.conf
or standalone.bat
configuration file, and also by setting system properties. If system properties are set using multiple ways, the values in the JBoss EAP configuration file standalone*.xml
override the other values.
Procedure
Setting the
JAVA_OPTS
environment variable:Linux
$ export JAVA_OPTS="-Xmx1024M"
Microsoft Windows
set JAVA_OPTS="Xmx1024M"
-
Alternatively, JVM settings can be added to the
standalone.conf
file, orstandalone.conf.bat
for Windows Server, in theEAP_HOME/bin
folder, which contains examples of options to pass to the JVM. Besides setting the
JAVA_OPTS
environment variable, you can set system properties using one of the following alternative ways:Execute the following command:
$ EAP_HOME/bin/standalone.sh -Dmyproperty=value
-
Edit the JBoss EAP configuration file,
standalone*.xml
.
If system properties are set using multiple ways, the values in the JBoss EAP configuration file standalone*.xml
override the other values, which may cause JBoss EAP startup issues. For example, if you have defined system settings in the JAVA_OPTS
environment variable and in the JBoss EAP configuration file, the values in JBoss EAP configuration override the values in JAVA_OPTS
.
8.2. Configuring JVM settings for a managed domain
In a JBoss EAP managed domain, you can define JVM settings at multiple levels. You can define custom JVM settings on a particular host, and then apply those settings to server groups, or to individual server instances.
By default, server groups and individual servers will inherit the JVM settings from their parent, but you can choose to override JVM settings at each level.
The JVM settings in domain.conf
, or domain.conf.bat
for Windows Server, are applied to the Java process of the JBoss EAP host controller, and not the individual JBoss EAP server instances controlled by that host controller.
8.2.1. Defining JVM settings on a host controller
You can define Java Virtual Machine (JVM) settings on a host controller, and apply those settings to server groups or individual servers. JBoss EAP comes with a default
JVM setting, but the following procedure demonstrates creating a new JVM setting named production_jvm
with some custom JVM settings and options. These settings are stored within the <jvm>
tag in host.xml
.
Prerequisites
- JBoss EAP is running as a managed domain.
Procedure
Define JVM settings by using the management CLI.
Syntax
/host=<HOST_NAME>/jvm=<SETTING_NAME>:add(heap-size=<HEAP_SIZE>, max-heap-size=<MAX_HEAP_SIZE>, max-permgen-size=<MAX_PERMANENT_GENERATION_SIZED>, stack-size=<STACK_SIZE>, jvm-options=["<JVM_OPTIONS>"])
Example
/host=exampleHost1/jvm=production_jvm:add(heap-size=2048m, max-heap-size=2048m, max-permgen-size=512m, stack-size=1024k, jvm-options=["-XX:-UseParallelGC"])
See Managed Domain JVM Configuration Attributes for descriptions of all available options.
Define JVM settings by using the management console.
-
Navigate to Runtime
Hosts in the management console. - Choose a host and click View.
- Select the JVMs tab to define the settings.
-
Navigate to Runtime
Next steps
Additional resources
8.2.2. Applying JVM settings to a server group
When creating a server group, you can specify a JVM configuration that all servers in the group will use. These settings for a server group are stored in domain.xml
.
Prerequisites
- JBoss EAP is running as a managed domain.
You have defined JVM settings for a host controller.
For more information, see Defining JVM settings on a host controller.
Procedure
Applying JVM settings to a server group by using the management CLI.
Create a server group name
exampleGroupA
that uses theproduction_jvm
JVM settings./server-group=exampleGroupA:add(profile=default,socket-binding-group=standard-sockets) /server-group=exampleGroupA/jvm=production_jvm:add
You can also override specific JVM settings at the server group level. For example, to set a different heap size, you can use the following command:
/server-group=exampleGroupA/jvm=production_jvm:write-attribute(name=heap-size,value="1024m")
After applying the above command, the server group
groupA
will inherit the JVM settings fromproduction_jvm
, except for the heap size which has an overridden value of1024m
.Applying JVM settings to a server group by using the management console.
-
Navigate to Runtime
Server Groups. - Choose a server group and click View.
- Select the JVMs tab to apply the settings.
-
Navigate to Runtime
Additional resources
8.2.3. Applying JVM settings to an individual server in a server group
By default, an individual JBoss EAP server instance will inherit the JVM settings of the server group it belongs to. However, you can choose to override the inherited settings with another complete JVM setting definition from the host controller, or choose to override specific JVM settings. These settings for an individual server are stored in host.xml
.
Prerequisites
- JBoss EAP is running as a managed domain.
You have applied JVM settings to a server group.
For more information, see Applying JVM settings to a server group.
Procedure
Applying JVM settings to an individual server by using the management CLI.
Override the JVM definition in the Applying JVM settings to a server group procedure, and set the JVM settings for
server-one
to thedefault
JVM definition:/host=exampleHost1/server-config=server-one/jvm=default:add
Also, similar to server groups, you can override specific JVM settings at the server level. For example, to set a different heap size, you can use the following command:
/host=exampleHost1/server-config=server-one/jvm=default:write-attribute(name=heap-size,value="1024m")
Applying JVM settings to an individual server by using the management console.
-
Navigate to Runtime
Hosts. - Choose the host, and click View on the server.
- Selecting the JVMs tab to apply settings.
-
Navigate to Runtime
Additional resources
8.3. Viewing the JVM resource status in the mananagement console
You can view the status of JVM resources, such as heap and thread usage, for standalone or managed domain servers from the management console. While statistics are not displayed in real time, you can click Refresh to provide an up-to-date overview of JVM resources.
Prerequisites
- JBoss EAP is running.
Procedure
View the JVM status for a standalone JBoss EAP server:
- Navigate to the Runtime tab, select the server, and select Status.
View JVM status for a JBoss EAP server in a managed domain:
-
Navigate to Runtime
Hosts, select the host and server, and select Status.
-
Navigate to Runtime
The following heap usage information is displayed:
- Max
- The maximum amount of memory that can be used for memory management.
- Used
- The amount of used memory.
- Committed
- The amount of memory that is committed for the Java Virtual Machine to use.
Other information, such as JVM uptime and thread usage, is also available.
For information about optimizing JVM performance, see JVM tuning in the Performance tuning for JBoss EAP guide.