Reset all index and input data and call gc, does NOT erase index/dir, does NOT clear statistics.
This contains ResetInputs.
Other side effects: writers/readers nullified, closed.
Index is NOT erased.
Directory is NOT erased.
Fields inherited from class org.apache.lucene.benchmark.byTask.tasks.PerfTask
Perform the task once (ignoring repetitions specification)
Return number of work items done by this task.
For indexing that can be number of docs added.
For warming that can be number of scanned items, etc.