Remove AcceleratorConnector.device_type

[DuYicong515]

Proposed refactor

Remove the property AcceleratorConnector.device_type and migrate its usage
https://github.com/PyTorchLightning/pytorch-lightning/blob/550d3a640d1bfeb731a16b2996d3160f0f7eb071/pytorch_lightning/trainer/connectors/accelerator_connector.py#L766-L775

Alternative

Check isinstance(Trainer.accelerator, [CPU/GPU/TPU/IPU]Accelerator) to get the device type.

Motivation

Remove deprecated accelerator_connector properties and deprecate Trainer properties accordingly.

AcceleratorConnector.device_type was not used within PytorchLightning anymore and those connector properties were never meant to be public.

Remove the property AcceleratorConnector.device_type, which is not used.

Additional context

No other usage, should be a safe remove

cc @justusschock @awaelchli @rohitgr7 @four4fish

[carmocca]

In the linked PR, I see the property was not deprecated previously but just removed.

Was this discussed somewhere? Is the assumption that we don't deprecate connector properties? Or some other reasoning?

[four4fish]

In the linked PR, I see the property was not deprecated previously but just removed.

Was this discussed somewhere? Is the assumption that we don't deprecate connector properties? Or some other reasoning?

@carmocca this is one of the follow ups in #11449, all these properties below L768 are not used anymore and can be removed. I think you already removed the trainer.device_type?

[carmocca]

I think you already removed the trainer.device_type?

I did, but that was prefixed by _: #11992

Personally, I'm okay with removing this. Properties and attributes inside the connectors were never meant to be public. I just wanted to raise awareness about this.

[krshrimali]

Just did a quick google search, to see if anywhere in a blog/docs, anyone has used device_type, and found no relevant results. So looks like removal is safe, but just putting this question for someone who comes to this issue for context: What is the suggested alternate (if any)? If a user wants to know the device type of the AcceleratorConnector object, how should they do it now? (except isinstance(obj, [CPU/GPU/TPU/IPU]Accelerator))

[DuYicong515]

@krshrimali Thanks for the suggestion! I feel getting the device_type string are not recommended now. (The _AcceleratorType is an internal enum instead).

The best alternative is to check isinstance(Trainer.acclerator, [CPU/GPU/TPU/IPU]Accelerator) whenever they want to know the accelerator type they are using? I've added this alternative to the issue descriptions.

Any other alternatives we should consider?

[krshrimali]

@krshrimali Thanks for the suggestion! I feel getting the device_type string are not recommended now. (The _AcceleratorType is an internal enum instead).

The best alternative is to check isinstance(Trainer.acclerator, [CPU/GPU/TPU/IPU]Accelerator) whenever they want to know the accelerator type they are using? I've added this alternative to the issue descriptions.

Any other alternatives we should consider?

Thanks for the response, I guess this is okay then. I didn't see any usage of device_type as such, so this is fine. Thank you!

Also, thanks for updating the description. Looks great now!

[four4fish]

I think you already removed the trainer.device_type?

I did, but that was prefixed by _: #11992

Personally, I'm okay with removing this. Properties and attributes inside the connectors were never meant to be public. I just wanted to raise awareness about this.

Thanks for the hands up, we have a bunch of properties in accl_conn can be removed like this. The trainer._accelerator_connector is already private, I think it's safe to remove properties in it directly?