WildFly and Garbage Collection Logging

External

• How to enable Garbage Collection (GC) logging in EAP 6 domain mode https://access.redhat.com/solutions/269023
• Preventing GC log file overwrites upon restart in domain mode https://access.redhat.com/solutions/1325293
• How to rotate gc log file configured in domain mode in EAP 6? https://access.redhat.com/solutions/1132613

Internal

• WildFly Configuration
• Logging Subsystem - GC Logging

Overview

GC logging is enabled by default for standalone mode (to verify form which version on). It generates output to $JBOSS_HOME/standalone/log/gc.log.<digit>. The system uses log rotation with the number of log files limited to 5, and the size of each file limited to 3 MB.

Enabling GC Logging in Standalone Mode

TODO.

Enabling GC Logging in Domain Mode

Server Node

The GC logging can be enabled for a specific server node, or generically, across the server group.

To enable GC logging for just one server node, modify the corresponding <jvm> declaration in the host.xml file.

To enable GC logging for an entire server group, edit the <ivm-options> section corresponding to the <jvm> configuration specified for the server group, in domain.xml.

In both cases, add the following JVM options:

<jvm-options>
    <option value="-verbose:gc"/>
    <option value="-Xloggc:${jboss.server.log.dir}/gc.log"/>
    <option value="-XX:+PrintGCDetails"/>
    <option value="-XX:+PrintGCDateStamps"/>
</jvm-options>

Option values cannot contain system properties, they cannot be resolved:

java.lang.IllegalStateException: WFLYCTL0211: Cannot resolve expression '-Xloggc:/opt/jdg/domain/servers/${jboss.server.name}/log/gc.log'

Host Controller

TODO.