question: The call of training_step and validation_step .etc.
context: Anyone help me where did these funcs been called in the core parts? I expect it to be called in the loop instance of trainer however not. Quite confused about this.
answer: depends upon the configuration but in a general case here: 
    
      
        pytorch-lightning/pytorch_lightning/plugins/training_type/training_type_plugin.py
      
      
          Lines 217 to 230
        in
        454e93b
      
    
    
      
  
          
            
             def training_step(self, *args, **kwargs): 
          
  
          
            
                 return self.model.training_step(*args, **kwargs) 
          
  
          
            
              
          
  
          
            
             def post_training_step(self): 
          
  
          
            
                 pass 
          
  
          
            
              
          
  
          
            
             def validation_step(self, *args, **kwargs): 
          
  
          
            
                 return self.model.validation_step(*args, **kwargs) 
          
  
          
            
              
          
  
          
            
             def test_step(self, *args, **kwargs): 
          
  
          
            
                 return self.model.test_step(*args, **kwargs) 
          
  
          
            
              
          
  
          
            
             def predict_step(self, *args, **kwargs): 
          
  
          
            
                 return self.model.predict_step(*args, **kwargs) 
          
      
    
  
  
  call sequence is loop -> accelerators -> training_type_plugin -> actual call