convert warning cache usage to rank_zero_only in WandbLogger (#8764)

Author: awaelchli

pytorch_lightning/loggers/wandb.py

@@ -29,9 +29,7 @@
 from pytorch_lightning.utilities import _module_available, rank_zero_only
 from pytorch_lightning.utilities.exceptions import MisconfigurationException
 from pytorch_lightning.utilities.imports import _compare_version
-from pytorch_lightning.utilities.warnings import WarningCache
-
-warning_cache = WarningCache()
+from pytorch_lightning.utilities.warnings import rank_zero_deprecation, rank_zero_warn
 
 _WANDB_AVAILABLE = _module_available("wandb")
 _WANDB_GREATER_EQUAL_0_10_22 = _compare_version("wandb", operator.ge, "0.10.22")
@@ -129,7 +127,7 @@ def __init__(
             )
 
         if log_model and not _WANDB_GREATER_EQUAL_0_10_22:
-            warning_cache.warn(
+            rank_zero_warn(
                 f"Providing log_model={log_model} requires wandb version >= 0.10.22"
                 " for logging associated model metadata.\n"
                 "Hint: Upgrade with `pip install --ugrade wandb`."
@@ -186,7 +184,7 @@ def experiment(self) -> Run:
             if wandb.run is None:
                 self._experiment = wandb.init(**self._wandb_init)
             else:
-                warning_cache.warn(
+                rank_zero_warn(
                     "There is a wandb run already in progress and newly created instances of `WandbLogger` will reuse"
                     " this run. If this is not desired, call `wandb.finish()` before instantiating `WandbLogger`."
                 )

tests/loggers/test_wandb.py

@@ -56,8 +56,8 @@ def test_wandb_logger_init(wandb):
     # verify default resume value
     assert logger._wandb_init["resume"] == "allow"
 
-    _ = logger.experiment
-    assert any("There is a wandb run already in progress" in w for w in pytorch_lightning.loggers.wandb.warning_cache)
+    with pytest.warns(UserWarning, match="There is a wandb run already in progress"):
+        _ = logger.experiment
 
     logger.log_metrics({"acc": 1.0}, step=3)
     wandb.init.assert_called_once()