lightning/pl_examples/basic_examples/README.md

## Basic Examples   
Use these examples to test how lightning works.   

#### MNIST
Trains MNIST where the model is defined inside the LightningModule.
```bash
# cpu
python mnist.py

# gpus (any number)
python mnist.py

# dataparallel
python mnist.py --gpus 2 --distributed_backend 'dp'
```

---   
#### Image classifier
Generic image classifier with an arbitrary backbone (ie: a simple system)
```bash
# cpu
python image_classifier.py

# gpus (any number)
python image_classifier.py --gpus 2

# dataparallel
python image_classifier.py --gpus 2 --distributed_backend 'dp'
```

---   
#### Autoencoder
Showing the power of a system... arbitrarily complex training loops
```bash
# cpu
python autoencoder.py

# gpus (any number)
python autoencoder.py --gpus 2

# dataparallel
python autoencoder.py --gpus 2 --distributed_backend 'dp'
```
---    
# Multi-node example   

This demo launches a job using 2 GPUs on 2 different nodes (4 GPUs total).
To run this demo do the following:

1. Log into the jumphost node of your SLURM-managed cluster.  
2. Create a conda environment with Lightning and a GPU PyTorch version.   
3. Choose a script to submit    

#### DDP  
Submit this job to run with DistributedDataParallel (2 nodes, 2 gpus each)
```bash
sbatch submit_ddp_job.sh YourEnv
```

#### DDP2  
Submit this job to run with a different implementation of DistributedDataParallel.
In this version, each node acts like DataParallel but syncs across nodes like DDP.
```bash
sbatch submit_ddp2_job.sh YourEnv
```