[BUG] Check environ before selecting a seed to prevent warning message (

#4743)

* Check environment var independently to selecting a seed to prevent unnecessary warning message

* Add if statement to check if PL_GLOBAL_SEED has been set

* Added seed test to ensure that the seed stays the same, in case

* if

* Delete global seed after test has finished

* Fix code, add tests

* Ensure seed does not exist before tests start

* Refactor test based on review, add log call

* Ensure we clear the os environ in patched dict

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: Carlos Mocholí <carlossmocholi@gmail.com>
Co-authored-by: chaton <thomas@grid.ai>
(cherry picked from commit 635df27)

pytorch_lightning/utilities/seed.py

@@ -20,8 +20,8 @@
 
 import numpy as np
 import torch
-
 from pytorch_lightning import _logger as log
+from pytorch_lightning.utilities import rank_zero_warn
 
 
 def seed_everything(seed: Optional[int] = None) -> int:
@@ -41,18 +41,17 @@ def seed_everything(seed: Optional[int] = None) -> int:
 
  try:
  if seed is None:
- seed = os.environ.get("PL_GLOBAL_SEED", _select_seed_randomly(min_seed_value, max_seed_value))
+ seed = os.environ.get("PL_GLOBAL_SEED")
  seed = int(seed)
  except (TypeError, ValueError):
  seed = _select_seed_randomly(min_seed_value, max_seed_value)
+ rank_zero_warn(f"No correct seed found, seed set to {seed}")
 
- if (seed > max_seed_value) or (seed < min_seed_value):
- log.warning(
- f"{seed} is not in bounds, \
- numpy accepts from {min_seed_value} to {max_seed_value}"
- )
+ if not (min_seed_value <= seed <= max_seed_value):
+ rank_zero_warn(f"{seed} is not in bounds, numpy accepts from {min_seed_value} to {max_seed_value}")
  seed = _select_seed_randomly(min_seed_value, max_seed_value)
 
+ log.info(f"Global seed set to {seed}")
  os.environ["PL_GLOBAL_SEED"] = str(seed)
  random.seed(seed)
  np.random.seed(seed)
@@ -62,6 +61,4 @@ def seed_everything(seed: Optional[int] = None) -> int:
 
 
 def _select_seed_randomly(min_seed_value: int = 0, max_seed_value: int = 255) -> int:
- seed = random.randint(min_seed_value, max_seed_value)
- log.warning(f"No correct seed found, seed set to {seed}")
- return seed
+ return random.randint(min_seed_value, max_seed_value)

tests/utilities/test_seed.py

@@ -0,0 +1,55 @@
+import os
+
+from unittest import mock
+import pytest
+
+import pytorch_lightning.utilities.seed as seed_utils
+
+
+@mock.patch.dict(os.environ, {}, clear=True)
+def test_seed_stays_same_with_multiple_seed_everything_calls():
+ """
+ Ensure that after the initial seed everything,
+ the seed stays the same for the same run.
+ """
+ with pytest.warns(UserWarning, match="No correct seed found"):
+ seed_utils.seed_everything()
+ initial_seed = os.environ.get("PL_GLOBAL_SEED")
+
+ with pytest.warns(None) as record:
+ seed_utils.seed_everything()
+ assert not record # does not warn
+ seed = os.environ.get("PL_GLOBAL_SEED")
+
+ assert initial_seed == seed
+
+
+@mock.patch.dict(os.environ, {"PL_GLOBAL_SEED": "2020"}, clear=True)
+def test_correct_seed_with_environment_variable():
+ """
+ Ensure that the PL_GLOBAL_SEED environment is read
+ """
+ assert seed_utils.seed_everything() == 2020
+
+
+@mock.patch.dict(os.environ, {"PL_GLOBAL_SEED": "invalid"}, clear=True)
+@mock.patch.object(seed_utils, attribute='_select_seed_randomly', new=lambda *_: 123)
+def test_invalid_seed():
+ """
+ Ensure that we still fix the seed even if an invalid seed is given
+ """
+ with pytest.warns(UserWarning, match="No correct seed found"):
+ seed = seed_utils.seed_everything()
+ assert seed == 123
+
+
+@mock.patch.dict(os.environ, {}, clear=True)
+@mock.patch.object(seed_utils, attribute='_select_seed_randomly', new=lambda *_: 123)
+@pytest.mark.parametrize("seed", (10e9, -10e9))
+def test_out_of_bounds_seed(seed):
+ """
+ Ensure that we still fix the seed even if an out-of-bounds seed is given
+ """
+ with pytest.warns(UserWarning, match="is not in bounds"):
+ actual = seed_utils.seed_everything(seed)
+ assert actual == 123