From e7f15e4e89662bf30c43218681f66d165295a26a Mon Sep 17 00:00:00 2001
From: William Falcon <falc@fb.com>
Date: Sat, 5 Oct 2019 15:39:37 -0400
Subject: [PATCH] cleaning up demos

---
 pytorch_lightning/trainer/trainer.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/pytorch_lightning/trainer/trainer.py b/pytorch_lightning/trainer/trainer.py
index 650af0fd..0b6a18f6 100644
--- a/pytorch_lightning/trainer/trainer.py
+++ b/pytorch_lightning/trainer/trainer.py
@@ -704,13 +704,14 @@ class Trainer(TrainerIO):
                         warnings.warn(msg)
                         break
 
-        # wait for all processes to catch up
-        dist.barrier()
+        if self.use_ddp or self.use_ddp2:
+            # wait for all processes to catch up
+            dist.barrier()
 
-        # load each dataloader
-        self.get_train_dataloader()
-        self.get_test_dataloaders()
-        self.get_val_dataloaders()
+            # load each dataloader
+            self.get_train_dataloader()
+            self.get_test_dataloaders()
+            self.get_val_dataloaders()
 
     # -----------------------------
     # MODEL TRAINING