Self-Supervised Learning Image Classification with Momentum Contrast

This is the final competition for NYU course CSCI-GA 2572 Deep Learning Spring 2021.

Instructor: Yann LeCun and Alfredo Canziani.

Deep Learning Final Competition Team DL09

Members:

Arthur Jinyue Guo (jg5505)

Yaowei Zong (yz7413)

Read the final report here.

Code Structure

src

source code

model
- Adopted MoCO v2
  - https://github.com/facebookresearch/moco
  - https://medium.com/analytics-vidhya/simclr-with-less-computational-constraints-moco-v2-in-pytorch-3d8f3a8f8bf2

scripts

Sbatch files to submit jobs on Greene HPC

pretrain.sbatch:
- pretraining on unlabeled images for 100 epochs.
pretrain_continue.sbatch:
- script for resume pretraining.
train.sbatch:
- training on train dataset for 100 epochs.
train_extra.sbatch:
- training with extra labels.
finetune.sbatch
- run fine tuning after training.
eval.sbatch:
- evaluating on validation set.

Replicate Instructions

(change dl09 to your hpc account for sbatch scipts and directories)

Request a CPU node on Greene log-4.
Clone this repo on the CPU node (GCP node).

Make sure you have the following files and directories:

# data file
/scratch/DL21SP/student_dataset.sqsh

# env files
/scratch/DL21SP/conda_fixed.sqsh
/share/apps/images/cuda11.1-cudnn8-devel-ubuntu18.04.sif

# log dir
$SCRATCH/log/

# pretrain checkpoints dir
$SCRATCH/dl09/pre_checkpoints

# train checkpoints dir
$SCRATCH/dl09/checkpoints

# train with extra label checkpoints dir
$SCRATCH/dl09/extra_checkpoints

# finetune dir (optional if you don't run fineturn)
$SCRATCH/dl09/fine_tune_checkpoints

Pretraining: run the following (takes > 60 hours with single T4 GPU)
```
cd $HOME/dl09/scripts
sbatch pretrain.sbatch
```
Note: if the pretraining job got killed, change the following args to the correct checkpoint and run sbatch pretrain_continue.sbatch to continue the training.
```
--resume $SCRATCH/dl09/pre_checkpoints/checkpoint_082.pth
--start-epoch 83
```
Training: run the following (takes > 1 hour with single T4 GPU)
```
cd $HOME/dl09/scripts
sbatch train.sbatch
```
Note: if you didn't finish 100 epochs, change the --pretrained $SCRATCH/dl09/pre_checkpoints/checkpoint_100.pth inside train.sbatch to the correct checkpoint file.
Training with extra labels:

Prepare the extra train image dataset with corresponding labeling file.

Change the line inside train_extra.sbatch with your training dataset:
```
cp -rp /scratch/jg5505/dl09/dataset /tmp/dataset
```
Then run
```
sbatch train_extra.sbatch
```
Fine Tuning (optional):

If you run finetuning, make sure to change finetune.sbatch with the correct checkpoint file from the step above: model_sub.pth. (model_best_{epoch}_{acc}.pth contains extra states)

You might get worse result. We didn't use the result from this for submission.
Evaluating:

To test the model on validation dataset, put the checkpoint(model_sub.pth) from training step in this location: $SCRATCH/model.pth, then run
```
sbatch eval.sbatch
```
Make sure you have src/submission.py correctly defined.

Labeling request

At the time of labeling request task, our model was not performing as expected.

Our initial plan for selecting bad images is:

During the pre-training stage, a random sample of size 12,800 images from the unlabeled dataset is selected.
After pre-training for certain epochs, the indices of such sampler dataset and the losses and accuracy are recorded.
Repeat the above step 40 times (i.e 512,000/12,800 such random samplers), the images with the worst losses and accuracies are selected for this job.

We ended up selecting 12,800 random indices from the unlabeled dataset.

Result

Due to time limiting and lacking one team member ( other teams have 3 or 4 members), we didn't have enough time to run a full pretraining and finetuning, thus the final submission only has a 15.98% validation accuracy (5.94% with extra labels).

luke0zong/ssl-classification-movo-v2