Lightning-AI / Lightning-AI/pytorch-lightning
can't fit with ddp_notebook on a Vertex AI Workbench instance (CUDA initialized)
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Description
### Bug description
Using this minimal code example:
```
import torch
import lightning as L
print(torch.cuda.is_initialized())
trainer = L.Trainer(
accelerator="auto",
strategy="ddp_notebook",
devices="auto",
max_epochs=1,
# callbacks=callbacks,
log_every_n_steps=1
)
print(torch.cuda.is_initialized())
```
On Google Colab with a T4 attached, both print statements print "False" as expected.
On a Vertex AI Workbench instance with a T4 attached, the second statement prints "True"; merely instantiating the Trainer initializes cuda. This prevents fitting with DDP.
What could be causing this, and is there any way to work around it?
### What version are you seeing the problem on?
v2.2
### How to reproduce the bug
_No response_
### Error messages and logs
```
# Error messages and logs here please
```
### Environment
Current environment
```
#- Lightning Component (e.g. Trainer, LightningModule, LightningApp, LightningWork, LightningFlow):
#- PyTorch Lightning Version (e.g., 1.5.0):
#- Lightning App Version (e.g., 0.5.2):
#- PyTorch Version (e.g., 2.0):
#- Python version (e.g., 3.9):
#- OS (e.g., Linux):
#- CUDA/cuDNN version:
#- GPU models and configuration:
#- How you installed Lightning(`conda`, `pip`, source):
#- Running environment of LightningApp (e.g. local, cloud):
```
### More info
_No response_
cc @justusschock @lantiga
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the minimal Trainer example in the issue and compare torch.cuda.is_initialized() before and after Trainer construction on Vertex AI Workbench versus Colab. Check the Vertex environment details and DDP notebook initialization path; done means identifying why Trainer initializes CUDA there and documenting a verified workaround or fix.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python, pytorch
- Domain
- distributed-systems, machine-learning
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100