text: Title: why failed to allocate GPU's memory
  Body: i write a function:
  
  ```python
  def updatepkl(business):
      file_list = os.listdir("FR/dataset/" + business)
          for file in file_list:
  	    file_path = 'FR/dataset/' + business + '/' + file
  	    if os.path.isdir(file_path):
  	        for i in os.listdir(file_path):
  		    DeepFace.find(img_path=file_path + '/' + i, db_path="FR/dataset/" + business + '/',
                       model_name='ArcFace', detector_backend='dlib',
                      distance_metric="euclidean_l2", enforce_detection=False)  # update pkl file
  
  ```
  When I execute this method, the GPU's memory is occupied greatly (14G,  total:16G). 
  When I call it again, the following error occurs: 
  ```
  tensorflow.python.framework.errors_impl.ResourceExhaustedError: {{function_node __wrapped__AddV2_device_/job:localhost/replica:0/task:0/device:GPU:0}} failed to allocate memory [Op:AddV2]
  ```
  Please explain why this situation occurs.
  thanks
  
  