add dali v3 (#412)

add dali

tools/train.py

@@ -112,14 +112,14 @@ def main(args):
         train_reader = Reader(config, 'train')()
         train_dataloader.set_sample_list_generator(train_reader, place)
         if config.validate:
-            valid_reader = Reader(config, 'valid')()
-            valid_dataloader.set_sample_list_generator(valid_reader, place)
+            if int(os.getenv("PADDLE_TRAINER_ID", 0)) == 0:
+                valid_reader = Reader(config, 'valid')()
+                valid_dataloader.set_sample_list_generator(valid_reader, place)
             compiled_valid_prog = program.compile(config, valid_prog)
-
     else:
         import dali
         train_dataloader = dali.train(config)
-        if config.validate and int(os.getenv("PADDLE_TRAINER_ID", 0)):
+        if config.validate:
             if int(os.getenv("PADDLE_TRAINER_ID", 0)) == 0:
                 valid_dataloader = dali.val(config)
             compiled_valid_prog = program.compile(config, valid_prog)