A task to provide "nice-ness" to the current thread, and/or to query the current value. Examples:

 <nice currentPriority="current.value" >

Set currentPriority to the current priority

 <nice newPriority="10" >

Raise the priority of the build process (But not forked programs)

 <nice currentPriority="old" newPriority="3" >

Lower the priority of the build process (But not forked programs), and save the old value to the property old.