fix gpus default for Trainer.add_argparse_args (#6898)

CHANGELOG.md

@@ -225,6 +225,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed `EarlyStopping` logic when `min_epochs` or `min_steps` requirement is not met ([#6705](https://github.com/PyTorchLightning/pytorch-lightning/pull/6705))
 
 
+- Fixed `--gpus` default for parser returned by `Trainer.add_argparse_args` ([#6898](https://github.com/PyTorchLightning/pytorch-lightning/pull/6898))
+
+
 ## [1.2.7] - 2021-04-06
 
 ### Fixed

pytorch_lightning/utilities/argparse.py

@@ -232,7 +232,6 @@ def add_argparse_args(
 
         if arg == 'gpus' or arg == 'tpu_cores':
             use_type = _gpus_allowed_type
-            arg_default = _gpus_arg_default
 
         # hack for types in (int, float)
         if len(arg_types) == 2 and int in set(arg_types) and float in set(arg_types):
@@ -287,10 +286,6 @@ def _gpus_allowed_type(x) -> Union[int, str]:
         return int(x)
 
 
-def _gpus_arg_default(x) -> Union[int, str]:
-    return _gpus_allowed_type(x)
-
-
 def _int_or_float_type(x) -> Union[int, float]:
     if '.' in str(x):
         return float(x)

pytorch_lightning/utilities/device_parser.py

@@ -59,11 +59,6 @@ def parse_gpu_ids(gpus: Optional[Union[int, str, List[int]]]) -> Optional[List[i
     If no GPUs are available but the value of gpus variable indicates request for GPUs
     then a MisconfigurationException is raised.
     """
-
-    # nothing was passed into the GPUs argument
-    if callable(gpus):
-        return None
-
     # Check that gpus param is None, Int, String or List
     _check_data_type(gpus)
 
@@ -97,10 +92,6 @@ def parse_tpu_cores(tpu_cores: Union[int, str, List]) -> Optional[Union[List[int
     Returns:
         a list of tpu_cores to be used or ``None`` if no TPU cores were requested
     """
-
-    if callable(tpu_cores):
-        return None
-
     _check_data_type(tpu_cores)
 
     if isinstance(tpu_cores, str):

tests/loggers/test_wandb.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 import os
 import pickle
-import types
 from argparse import ArgumentParser
 from unittest import mock
 
@@ -172,11 +171,10 @@ def test_wandb_sanitize_callable_params(tmpdir):
     params.wrapper_something_wo_name = lambda: lambda: '1'
     params.wrapper_something = wrapper_something
 
-    assert isinstance(params.gpus, types.FunctionType)
     params = WandbLogger._convert_params(params)
     params = WandbLogger._flatten_dict(params)
     params = WandbLogger._sanitize_callable_params(params)
-    assert params["gpus"] == '_gpus_arg_default'
+    assert params["gpus"] == "None"
     assert params["something"] == "something"
     assert params["wrapper_something"] == "wrapper_something"
     assert params["wrapper_something_wo_name"] == "<lambda>"

tests/trainer/test_trainer_cli.py

@@ -175,12 +175,13 @@ def test_argparse_args_parsing(cli_args, expected):
     assert Trainer.from_argparse_args(args)
 
 
-@pytest.mark.parametrize(['cli_args', 'expected_gpu'], [
-    pytest.param('--gpus 1', [0]),
-    pytest.param('--gpus 0,', [0]),
+@pytest.mark.parametrize(['cli_args', 'expected_parsed', 'expected_device_ids'], [
+    pytest.param('', None, None),
+    pytest.param('--gpus 1', 1, [0]),
+    pytest.param('--gpus 0,', '0,', [0]),
 ])
 @RunIf(min_gpus=1)
-def test_argparse_args_parsing_gpus(cli_args, expected_gpu):
+def test_argparse_args_parsing_gpus(cli_args, expected_parsed, expected_device_ids):
     """Test multi type argument with bool."""
     cli_args = cli_args.split(' ') if cli_args else []
     with mock.patch("argparse._sys.argv", ["any.py"] + cli_args):
@@ -188,8 +189,9 @@ def test_argparse_args_parsing_gpus(cli_args, expected_gpu):
         parser = Trainer.add_argparse_args(parent_parser=parser)
         args = Trainer.parse_argparser(parser)
 
+    assert args.gpus == expected_parsed
     trainer = Trainer.from_argparse_args(args)
-    assert trainer.data_parallel_device_ids == expected_gpu
+    assert trainer.data_parallel_device_ids == expected_device_ids
 
 
 @RunIf(min_python="3.7.0")

tests/utilities/test_argparse.py

@@ -7,7 +7,7 @@ import pytest
 
 from pytorch_lightning import Trainer
 from pytorch_lightning.utilities.argparse import (
-    _gpus_arg_default,
+    _gpus_allowed_type,
     _int_or_float_type,
     add_argparse_args,
     from_argparse_args,
@@ -205,9 +205,9 @@ def test_add_argparse_args_no_argument_group():
     assert args.my_parameter == 2
 
 
-def test_gpus_arg_default():
-    assert _gpus_arg_default('1,2') == '1,2'
-    assert _gpus_arg_default('1') == 1
+def test_gpus_allowed_type():
+    assert _gpus_allowed_type('1,2') == '1,2'
+    assert _gpus_allowed_type('1') == 1
 
 
 def test_int_or_float_type():