-XX:[+|-]IdleTuningCompactOnIdle

(Linux® only)

This option controls garbage collection processing with compaction when the state of the OpenJ9 VM is set to idle.

Restrictions: This option applies only to Linux® architectures when the Generational Concurrent (gencon) garbage collection policy is in use. This option is not effective if the object heap is configured to use large pages.

Syntax

    -XX:[+|-]IdleTuningCompactOnIdle
Setting Effect Default Default when running in a docker container
-XX:+IdleTuningCompactOnIdle Enable yes
-XX:-IdleTuningCompactOnIdle Disable yes

The default depends on whether or not the OpenJ9 VM is running in a container. As indicated in the table, when the VM is running in a container and the state is set to idle, the VM attempts to compact the object heap following a garbage collection cycle. The garbage collection cycle is controlled by the -XX:+IdleTuningGcOnIdle option, which is also enabled by default when the OpenJ9 VM is running inside a container.

If your application is not running in a container and you want to enable compaction as part of the idle-tuning process, set the -XX:+IdleTuningCompactOnIdle option on the command line when you start your application.

The -XX:+IdleTuningCompactOnIdle option can be used with the -XX:+IdleTuningMinIdleWaitTime, which controls the amount of time that the VM must be idle before an idle state is set. If a value for the -XX:+IdleTuningMinIdleWaitTime option is not explicitly specified, the VM sets a default value of 180 seconds.

See also