fix logged keys in mlflow logger (#4412)

* [#4411] fix gpu_log_memory with mlflow logger

* sanitize parenthesis instead of removing for all loggers

* apply regex for mlflow key sanitization

* replace ',' with '.' typo

* add single warning and test

Co-authored-by: Rohit Gupta <rohitgr1998@gmail.com>
Co-authored-by: chaton <thomas@grid.ai>

pytorch_lightning/loggers/mlflow.py

@@ -16,6 +16,8 @@
 MLflow
 ------
 """
+import re
+import warnings
 from argparse import Namespace
 from time import time
 from typing import Any, Dict, Optional, Union
@@ -151,6 +153,13 @@ class MLFlowLogger(LightningLoggerBase):
             if isinstance(v, str):
                 log.warning(f'Discarding metric with string value {k}={v}.')
                 continue
+
+            new_k = re.sub("[^a-zA-Z0-9_/. -]+", "", k)
+            if k != new_k:
+                warnings.warn(("MLFlow only allows '_', '/', '.' and ' ' special characters in metric name.\n",
+                               f"Replacing {k} with {new_k}."))
+            k = new_k
+
             self.experiment.log_metric(self.run_id, k, v, timestamp_ms, step)
 
     @rank_zero_only

tests/loggers/test_mlflow.py

@@ -137,7 +137,8 @@ def test_mlflow_logger_dirs_creation(tmpdir):
         assert set(os.listdir(tmpdir / exp_id)) == {run_id, 'meta.yaml'}
 
     model = EvalModelTemplate()
-    trainer = Trainer(default_root_dir=tmpdir, logger=logger, max_epochs=1, limit_val_batches=3)
+    trainer = Trainer(default_root_dir=tmpdir, logger=logger, max_epochs=1, limit_val_batches=3,
+                      log_gpu_memory=True)
     trainer.fit(model)
     assert set(os.listdir(tmpdir / exp_id)) == {run_id, 'meta.yaml'}
     assert 'epoch' in os.listdir(tmpdir / exp_id / run_id / 'metrics')