public BatchExecutor fitnessExecutor() {
			return _fitnessExecutor != null
				? _fitnessExecutor
				: BatchExecutor.of(executor());
		}
Return the batch executor, used for evaluating the fitness functions.

@since 8.0

@return the batch executor, used for evaluating the fitness functions
jenetics/src/main/java/io/jenetics/engine/Engine.java