The memory arguments defined in the domain.conf.bat file
are applicable to the processes of domain controller and process
controller. Ensure that you set these memory arguments on each node
of the cluster.
In a managed domain, the JVM settings are declared in the host.xml
and the domain.xml configuration files. Domain controller components
responsible for starting and stopping server processes use these
settings. In a standalone server instance, the server startup processes
can pass command line settings at startup. These settings can be
declared from the command line or from the System Properties screen
in the Management Console.
Managed Domain
An important feature of
the managed domain is the ability to define JVM settings at multiple
levels. You can configure custom JVM settings at the host level,
by server group, or by server instance. The more specialized child
elements override the parent configuration, allowing for the declaration
of specific server configurations without requiring exclusions at
the group or host level. This also allows the parent configuration
to be inherited by the other levels until settings are either declared
in the configuration files or passed at runtime.
JVM settings in the domain configuration file
The
following example shows a JVM declaration for a server group in
the domain_db.xml configuration file.
<server-groups>
<server-group name="main-server-group" profile="default">
<jvm name="default">
<heap size="64m " max-size="512m "/>
</jvm >
<socket-binding-group ref="standard-sockets"/>
</server-group>
</server-groups>
In this instance a server group
called main-server-group declares a heap size of 64 megabytes, and
a maximum heap size of 512 megabytes. Any server that belongs to
this group inherits these settings. You can change these settings
for the group as a whole, by the host, or the individual server.
The
following example shows a JVM declaration for a server group in
the host.xml configuration file.
<servers>
<server name="server-one" group="main-server-group" auto-start="true">
<jvm name="default">
<heap size="64m " max-size="256m "/>
</jvm >
</server>
</servers
In this instance, a server named server-one
belongs to the server group named main-servergroup, inheriting the
JVM settings from the default JVM group. In the previous example,
the main heap size for main-server-group was set at 512 megabytes.
By declaring the lower maximum heap size of 256 megabytes, server-one
can override the domain.xml settings to fine-tune performance to
the required levels.
