added auto port find

pytorch_lightning/models/trainer.py

@@ -570,7 +570,11 @@ class Trainer(TrainerIO):
         :return:
         """
         # sets the appropriate port
-        self.__find_open_port()
+        try:
+            port = os.environ['MASTER_PORT']
+        except Exception as e:
+            port = 12910
+            os.environ['MASTER_PORT'] = f'{port}'
 
         root_node = self.__resolve_root_node_address()
         os.environ['MASTER_ADDR'] = root_node

tests/test_models.py

@@ -113,6 +113,8 @@ def test_multi_gpu_model_ddp():
         warnings.warn('test_multi_gpu_model_ddp cannot run. Rerun on a node with 2+ GPUs to run this test')
         return
 
+    os.environ['MASTER_PORT'] = str(np.random.randint(12000, 19000, 1)[0])
+
     trainer_options = dict(
         progress_bar=False,
         max_nb_epochs=1,
@@ -137,6 +139,8 @@ def test_amp_gpu_ddp():
         warnings.warn('test_amp_gpu_ddp cannot run. Rerun on a node with 2+ GPUs to run this test')
         return
 
+    os.environ['MASTER_PORT'] = str(np.random.randint(12000, 19000, 1)[0])
+
     trainer_options = dict(
         progress_bar=True,
         max_nb_epochs=1,