`fit` hangs with a custom port on 2+ GPUs
🐛 Bug
The following seems to indefinitely hang:
To Reproduce
file: hangs.py
import os, random
from tests.base.boring_model import BoringModel
from pytorch_lightning import Trainer

def test(tmpdir):
    port = str(random.randint(1200, 1900))
    os.environ['MASTER_PORT'] = port

    trainer = Trainer(
        default_root_dir=tmpdir,
        progress_bar_refresh_rate=0,
        logger=False,
        max_epochs=2,
        limit_train_batches=10,
        limit_val_batches=10,
        gpus=2,
        distributed_backend='ddp'
    )
    trainer.fit(BoringModel())
pytest hangs.py
Expected behavior
Test runs
Environment
Current master