Raise error for devices for cpu not being int

Lightning-AI · Jul 20, 2021 · 25456e0 · 25456e0
1 parent 12634ca
commit 25456e0
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diff --git a/pytorch_lightning/trainer/connectors/accelerator_connector.py b/pytorch_lightning/trainer/connectors/accelerator_connector.py
@@ -413,6 +413,11 @@ def _map_devices_to_accelerator(self, accelerator: str) -> bool:
             self.parallel_device_ids = device_parser.parse_gpu_ids(self.devices)
             return True
         if accelerator == DeviceType.CPU:
+            if not isinstance(self.devices, int):
+                raise MisconfigurationException(
+                    "The flag `devices` only supports integer for `accelerator='cpu'`,"
+                    f" got `devices={self.devices}` instead."
+                )
             self.num_processes = self.devices
             return True
         return False

diff --git a/tests/accelerators/test_accelerator_connector.py b/tests/accelerators/test_accelerator_connector.py
@@ -713,3 +713,9 @@ def test_set_devices_if_none_gpu():
 
     trainer = Trainer(accelerator="gpu", gpus=2)
     assert trainer.devices == 2
+
+
+def test_devices_with_cpu_only_supports_integer():
+
+    with pytest.raises(MisconfigurationException, match="The flag `devices` only supports integer"):
+        Trainer(accelerator="cpu", devices="1,3")