Problems in multi-card distributed training

[nowbug]

The problem of distributed training blocking

Steps to Reproduce

1、Minimum code block

from otx.engine import Engine

engine = Engine(model="yolox_s", data_root="pwd")
engine.train(num_nodes=2)

2.I tried other code to troubleshoot my environment.

import lightning as L
from lightning.pytorch.demos.boring_classes import BoringModel

ngpus = 2
model = BoringModel()
trainer = L.Trainer(max_epochs=10,
devices=ngpus)

trainer.fit(model)

log:
Initializing distributed: GLOBAL_RANK: 0, MEMBER: 1/2
Initializing distributed: GLOBAL_RANK: 1, MEMBER: 2/2

distributed_backend=nccl
All distributed processes registered. Starting with 2 processes

Environment:

• OS:
• Framework version:
• Python version: 3.10
• OpenVINO version:
• CUDA/cuDNN version: 12.2
• GPU model and memory: 24G(4090)*2

[nowbug]

When I run it, it will card the owner. Initializing distributed: GLOBAL_RANK: 0, MEMBER: 1/2

[harimkang]

@eunwoosh could you take a look at this issue?

[harimkang]

I found some open issues related to this and commented on them.

• [Bug] No backend type associated with device type cpu Lightning-AI/torchmetrics#2477
• [Bug] RuntimeError: No backend type associated with device type cpu Lightning-AI/pytorch-lightning#18803

[eunwoosh]

Hi @nowbug , thanks for finding the issue. First of all I want to say that OTX 2.0 currently doesn't validate distributed training, so it can be a little bit unstable. Nevertheless, OTX is based on pytorch lightning, so I think distributed training is available in most cases. OTX have a plan to support distributed training in the near future, so it can become stable soon.
And I tested with your second code snippet, and I found a bug as @harimkang said. So, I opened PR to fix it.
I also found that distributed training is stuck in some cases, and I suspect number of dataset is cause of the problem. I'll fix that bug after finding more.

[nowbug]

@eunwoosh Thank you for your response. I'm looking forward to the upcoming versions of OTX.