# Engine pruning

When the TERR service reaches a certain percentage of capacity of usage, then the TERR service begins pruning TERR engines to free service resources.

Configuration property | Default setting | Description
--- | --- | ---
`engine.prune` | `10` | The time, in seconds, that a TERR engine can be idle before the TERR service prunes it.
`dynamic.prune.threshold` | `60` | The TERR service capacity at which idle pruning is engaged, as a percentage value. By default, when the TERR service reaches 60% capacity of usage, then it begins the idle-pruning process as specified by `engine.prune`. Set to `0` to always prune when a TERR engine is idle. Set to `100` to never prune when a TERR engine is idle.

For more information, see Service resource management scenarios.