taskA                                                                              
                                                                                                                  
                                                                                                                  
                                                                          dataaaa                                 
                                                                                                                  
                                                                                                                  
              OK                                                                                          NG      
                                              check                                                               
                                                                                                                  
                                                                                                                  
                                                                                                                  
                                                                                                                  
                                                                                                                  
                                                                                                                  
                                                                                                                  
                                         retry?                                                               true
                                                                                                                  
                                                                          false