add option 'find unused paramters' for trainer (#311)

configs/cyclegan_cityscapes.yaml

 epochs: 200
 output_dir: output_dir
+find_unused_parameters: True
 
 model:
   name: CycleGANModel

configs/cyclegan_horse2zebra.yaml

 epochs: 200
 output_dir: output_dir
+find_unused_parameters: True
 
 model:
   name: CycleGANModel

configs/esrgan_x4_div2k.yaml

 total_iters: 250000
 output_dir: output_dir
+find_unused_parameters: True
 # tensor range for function tensor2img
 min_max:
   (0., 1.)

configs/makeup.yaml

 epochs: 100
 output_dir: tmp
 checkpoints_dir: checkpoints
+find_unused_parameters: True
 
 model:
   name: MakeupModel

configs/realsr_bicubic_noise_x4_df2k.yaml

 total_iters: 60000
 output_dir: output_dir
+find_unused_parameters: True
 # tensor range for function tensor2img
 min_max:
   (0., 1.)

configs/realsr_kernel_noise_x4_dped.yaml

 total_iters: 60000
 output_dir: output_dir
+find_unused_parameters: True
 # tensor range for function tensor2img
 min_max:
   (0., 1.)

ppgan/engine/trainer.py

@@ -146,8 +146,10 @@ class Trainer:
 
     def distributed_data_parallel(self):
         paddle.distributed.init_parallel_env()
+        find_unused_parameters = self.cfg.get('find_unused_parameters', False)
         for net_name, net in self.model.nets.items():
-            self.model.nets[net_name] = paddle.DataParallel(net)
+            self.model.nets[net_name] = paddle.DataParallel(
+                net, find_unused_parameters=find_unused_parameters)
 
     def learning_rate_scheduler_step(self):
         if isinstance(self.model.lr_scheduler, dict):