Fixes #2942 (#2969)

* Fixes #2942 * doc fix
2020-08-13 21:54:57 -04:00 · 2020-08-13 21:54:57 -04:00 · 0c264689cb
parent 48f658fbb5
commit 0c264689cb
2 changed files with 3 additions and 3 deletions
--- a/pytorch_lightning/accelerators/ddp_backend.py
+++ b/pytorch_lightning/accelerators/ddp_backend.py
@ -87,7 +87,7 @@ class DDPBackend(object):
        command = [sys.executable] + command

        # since this script sets the visible devices we replace the gpus flag with a number
-        num_gpus = os.environ['CUDA_VISIBLE_DEVICES'].split(',').__len__()
+        num_gpus = os.environ.get('CUDA_VISIBLE_DEVICES', []).split(',').__len__()

        if '--gpus' in command:
            gpu_flag_idx = command.index('--gpus')