From 8217ebe029e590c56ba43d8731ab2001ecc9bac6 Mon Sep 17 00:00:00 2001
From: William Falcon <falc@fb.com>
Date: Sun, 21 Jul 2019 08:20:06 -0400
Subject: [PATCH] updated auto ddp for > 1 node

---
 pytorch_lightning/models/trainer.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pytorch_lightning/models/trainer.py b/pytorch_lightning/models/trainer.py
index ba47ab6c..91de1b69 100644
--- a/pytorch_lightning/models/trainer.py
+++ b/pytorch_lightning/models/trainer.py
@@ -150,6 +150,7 @@ class Trainer(TrainerIO):
         self.use_ddp = False
         self.use_dp = False
 
+
         # gpus come in as a string.
         # if gpus = -1 then use all available devices
         # otherwise, split the string using commas
@@ -176,6 +177,15 @@ class Trainer(TrainerIO):
             self.use_dp = distributed_backend == 'dp'
             self.use_ddp = distributed_backend == 'ddp'
 
+            # use ddp automatically if nb_gpu_nodes > 1
+            if nb_gpu_nodes > 1:
+                self.use_ddp = True
+                self.use_ddp = False
+                w = 'DataParallel does not support nb_gpu_nodes > 1. ' \
+                    'Switching to DistributedDataParallel for you. ' \
+                    'To silence this warning set distributed_backend=ddp'
+                warnings.warn(w)
+
         # process info
         self.proc_rank = 0