Training ShapeMask on Cloud TPU (TF 2.x)

This document demonstrates how to run the ShapeMask model using Cloud TPU with the COCO dataset.

The instructions below assume you are already familiar with running a model on Cloud TPU. If you are new to Cloud TPU, you can refer to the Quickstart for a basic introduction.

If you plan to train on a TPU Pod slice, review Training on TPU Pods to understand parameter changes required for Pod slices.

Objectives

Prepare the COCO dataset
Create a Cloud Storage bucket to hold your dataset and model output
Set up TPU resources for training and evaluation
Run training and evaluation on a single Cloud TPU or a Cloud TPU Pod

Costs

In this document, you use the following billable components of Google Cloud:

Compute Engine
Cloud TPU
Cloud Storage

To generate a cost estimate based on your projected usage, use the pricing calculator. New Google Cloud users might be eligible for a free trial.

Before you begin

Before starting this tutorial, check that your Google Cloud project is correctly set up.

Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

Go to project selector

Make sure that billing is enabled for your Google Cloud project.

This walkthrough uses billable components of Google Cloud. Check the Cloud TPU pricing page to estimate your costs. Be sure to clean up resources you create when you've finished with them to avoid unnecessary charges.

Cloud TPU single device training

This section provides information on setting up Cloud Storage, VM, and Cloud TPU resources for single device training.

If you plan to train on a TPU Pod slice, review Training on TPU Pods to understand the changes required to train on Pod slices.

In your Cloud Shell, create a variable for your project's ID.
```
export PROJECT_ID=project-id
```
Configure Google Cloud CLI to use the project where you want to create Cloud TPU.
```
gcloud config set project ${PROJECT_ID}
```
The first time you run this command in a new Cloud Shell VM, an Authorize Cloud Shell page is displayed. Click Authorize at the bottom of the page to allow gcloud to make Google Cloud API calls with your Google Cloud credentials.

Create a Service Account for the Cloud TPU project.

gcloud beta services identity create --service tpu.googleapis.com --project $PROJECT_ID

The command returns a Cloud TPU Service Account with following format:

service-PROJECT_NUMBER@cloud-tpu.iam.gserviceaccount.com

Prepare the COCO dataset

This tutorial uses the COCO dataset. The dataset needs to be in TFRecord format on a Cloud Storage bucket to be used for the training.

The bucket location must be in the same region as your virtual machine (VM) and your TPU node. VMs and TPU nodes are located in specific zones, which are subdivisions within a region.

The Cloud Storage bucket stores the data you use to train your model and the training results. The gcloud compute tpus tpu-vm tool used in this tutorial sets up default permissions for the Cloud TPU Service Account you set up in the previous step. If you want finer-grain permissions, review the access level permissions.

If you already have the COCO dataset prepared on a Cloud Storage bucket that is located in the zone you will be using to train the model, you can launch the TPU resources and prepare Cloud TPU for training. Otherwise, use the following steps to prepare the dataset.

In your Cloud Shell, configure gcloud with your project ID.

export PROJECT_ID=project-id
gcloud config set project ${PROJECT_ID}

In your Cloud Shell, create a Cloud Storage bucket using the following command:

Note: In the following command, replace bucket-name with the name you want to assign to your bucket.
```
gcloud storage buckets create gs://bucket-name --project=${PROJECT_ID} --location=us-central2
```

Create a Compute Engine VM to download and preprocess the dataset. For more information, see Create and start a Compute Engine instance.

$ gcloud compute instances create vm-name \
    --zone=us-central2-b \
    --image-family=ubuntu-2204-lts \
    --image-project=ubuntu-os-cloud \
    --machine-type=n1-standard-16 \
    --boot-disk-size=300GB

Connect to the Compute Engine VM using SSH:
```
$ gcloud compute ssh vm-name --zone=us-central2-b
```
When you connect to the VM, your shell prompt changes from username@projectname to username@vm-name.
Set up two variables, one for the storage bucket you created earlier and one for the directory that holds the training data (DATA_DIR) on the storage bucket.
```
(vm)$ export STORAGE_BUCKET=gs://bucket-name
```
```
(vm)$ export DATA_DIR=${STORAGE_BUCKET}/coco
```

Install the packages needed to pre-process the data.

(vm)$ sudo apt-get update && \
  sudo apt-get install python3-pip && \
  sudo apt-get install -y python3-tk && \
  pip3 install --user Cython matplotlib opencv-python-headless pyyaml Pillow numpy absl-py tensorflow && \
  pip3 install --user "git+https://github.com/cocodataset/cocoapi#egg=pycocotools&subdirectory=PythonAPI"

Run the download_and_preprocess_coco.sh script to convert the COCO dataset into a set of TFRecord files (*.tfrecord) that the training application expects.
```
(vm)$ git clone https://github.com/tensorflow/tpu.git
(vm)$ sudo bash tpu/tools/datasets/download_and_preprocess_coco.sh ./data/dir/coco
```
This installs the required libraries and then runs the preprocessing script. It outputs *.tfrecord files in your local data directory. The COCO download and conversion script takes approximately one hour to complete.
Copy the data to your Cloud Storage bucket.

After you convert the data into the TFRecord format, copy the data from local storage to your Cloud Storage bucket using the gcloud CLI. You must also copy the annotation files. These files help validate the model's performance.
```
(vm)$ gcloud storage cp ./data/dir/coco/*.tfrecord ${DATA_DIR}
(vm)$ gcloud storage cp ./data/dir/coco/raw-data/annotations/*.json ${DATA_DIR}
```
Disconnect from the Compute Engine VM:
```
(vm)$ exit
```
Your prompt should now be username@projectname, showing you are in the Cloud Shell.

Delete your Compute Engine VM:

$ gcloud compute instances delete vm-name \
--zone=us-central2-b

Launch the TPU resources and train the model

Use the gcloud command to launch the TPU resources.
```
$ gcloud compute tpus tpu-vm create shapemask-tutorial \
  --zone=europe-west4-a \
  --accelerator-type=v3-8 \
  --version=tpu-vm-tf-2.17.0-pjrt
```
Command flag descriptions

zone

The zone where you plan to create your Cloud TPU.

accelerator-type

The accelerator type specifies the version and size of the Cloud TPU you want to create. For more information about supported accelerator types for each TPU version, see TPU versions.

version

The Cloud TPU software version.

Note: If you have more than one project, you must specify the project ID with the --project flag.

For more information on the gcloud command, see the gcloud Reference.

Note: The first time you run gcloud compute tpus on a project it takes approximately 5 minutes to perform startup tasks such as SSH key propagation and API turnup.
Connect to the Compute Engine instance using SSH. When you are connected to the VM, your shell prompt changes from username@projectname to username@vm-name:
```
gcloud compute tpus tpu-vm ssh shapemask-tutorial --zone=europe-west4-a
```
Key Point: From this point on, a prefix of (vm) $ means you should run the command on the Compute Engine VM instance.

Install TensorFlow requirements.

(vm)$ pip3 install -r /usr/share/tpu/models/official/requirements.txt

The training script requires an extra package. Install it now:

(vm)$ pip3 install --user tensorflow-model-optimization>=0.1.3

Set the storage bucket name variable. Replace bucket-name with the name of your storage bucket:
```
(vm)$ export STORAGE_BUCKET=gs://bucket-name
```
Set the Cloud TPU name variable.
```
(vm)$ export TPU_NAME=local
```

Set the PYTHONPATH environment variable:

(vm)$ export PYTHONPATH="/usr/share/tpu/models:${PYTHONPATH}"

Change to directory that stores the model:

(vm)$ cd /usr/share/tpu/models/official/legacy/detection

Add some required environment variables:

(vm)$ export RESNET_CHECKPOINT=gs://cloud-tpu-checkpoints/retinanet/resnet50-checkpoint-2018-02-07
(vm)$ export DATA_DIR=${STORAGE_BUCKET}/coco
(vm)$ export TRAIN_FILE_PATTERN=${DATA_DIR}/train-*
(vm)$ export EVAL_FILE_PATTERN=${DATA_DIR}/val-*
(vm)$ export VAL_JSON_FILE=${DATA_DIR}/instances_val2017.json
(vm)$ export SHAPE_PRIOR_PATH=gs://cloud-tpu-checkpoints/shapemask/kmeans_class_priors_91x20x32x32.npy
(vm)$ export MODEL_DIR=${STORAGE_BUCKET}/shapemask

When creating your TPU, if you set the --version parameter to a version ending with -pjrt, set the following environment variables to enable the PJRT runtime:
```
  (vm)$ export NEXT_PLUGGABLE_DEVICE_USE_C_API=true
  (vm)$ export TF_PLUGGABLE_DEVICE_LIBRARY_PATH=/lib/libtpu.so
```

Train the ShapeMask model:

The following script runs a sample training that trains for just 100 steps and takes approxiately 10 minutes to complete on a v3-8 TPU. To train to convergence takes about 22,500 steps and approximately 6 hours on a v3-8 TPU.

(vm)$ python3 main.py \
  --strategy_type=tpu \
  --tpu=${TPU_NAME} \
  --model_dir=${MODEL_DIR} \
  --mode=train \
  --model=shapemask \
  --params_override="{train: {total_steps: 100, learning_rate: {init_learning_rate: 0.08, learning_rate_levels: [0.008, 0.0008], learning_rate_steps: [15000, 20000], }, checkpoint: { path: ${RESNET_CHECKPOINT},prefix: resnet50}, train_file_pattern: ${TRAIN_FILE_PATTERN}}, shapemask_head: {use_category_for_mask: true, shape_prior_path: ${SHAPE_PRIOR_PATH}}, shapemask_parser: {output_size: [640, 640]}}"

Command flag descriptions

strategy_type: To train the Shapemask model on a TPU, you must set the distribution_strategy to tpu.
tpu: The name of the Cloud TPU. This is set using the TPU_NAME environment variable.
model_dir: The directory where checkpoints and summaries are stored during model training. If the folder is missing, the program creates one. When using a Cloud TPU, the model_dir must be a Cloud Storage path (gs://...). You can reuse an existing folder to load current checkpoint data and to store additional checkpoints as long as the previous checkpoints were created using a Cloud TPU of the same size and TensorFlow version.
mode: Set this to train to train the model or eval to evaluate the model.
params_override: A JSON string that overrides default script parameters. For more information on script parameters, see /usr/share/models/official/legacy/detection/main.py.

When the training completes, a message similar to the following appears:

Train Step: 100/100  / loss = {'total_loss': 10.815635681152344,
'loss': 10.815635681152344, 'retinanet_cls_loss': 1.4915691614151,
'l2_regularization_loss': 4.483549118041992,
'retinanet_box_loss': 0.013074751943349838,
'shapemask_prior_loss': 0.17314358055591583,
'shapemask_coarse_mask_loss': 1.953366756439209,
'shapemask_fine_mask_loss': 2.216097831726074, 'model_loss': 6.332086086273193,
'learning_rate': 0.021359999} / training metric = {'total_loss': 10.815635681152344,
'loss': 10.815635681152344, 'retinanet_cls_loss': 1.4915691614151,
'l2_regularization_loss': 4.483549118041992,
'retinanet_box_loss': 0.013074751943349838,
'shapemask_prior_loss': 0.17314358055591583,
'shapemask_coarse_mask_loss': 1.953366756439209,
'shapemask_fine_mask_loss': 2.216097831726074,
'model_loss': 6.332086086273193, 'learning_rate': 0.021359999}

Run the script to evaluate the ShapeMask model. This takes about 10 minutes on a v3-8 TPU:

(vm)$ python3 main.py \
--strategy_type=tpu \
--tpu=${TPU_NAME} \
--model_dir=${MODEL_DIR} \
--checkpoint_path=${MODEL_DIR} \
--mode=eval_once \
--model=shapemask \
--params_override="{eval: { val_json_file: ${VAL_JSON_FILE}, eval_file_pattern: ${EVAL_FILE_PATTERN}, eval_samples: 5000 }, shapemask_head: {use_category_for_mask: true, shape_prior_path: ${SHAPE_PRIOR_PATH}}, shapemask_parser: {output_size: [640, 640]}}"

Command flag descriptions

strategy_type: To train the Shapemask model on a TPU, you must set the distribution_strategy to tpu.
tpu: The name of the Cloud TPU. This is set using the TPU_NAME environment variable.
model_dir: The directory where checkpoints and summaries are stored during model training. If the folder is missing, the program creates one. When using a Cloud TPU, the model_dir must be a Cloud Storage path (gs://...). You can reuse an existing folder to load current checkpoint data and to store additional checkpoints as long as the previous checkpoints were created using a Cloud TPU of the same size and TensorFlow version.
mode: Set this to train to train the model or eval to evaluate the model.
params_override: A JSON string that overrides default script parameters. For more information on script parameters, see /usr/share/models/official/legacy/detection/main.py.

When the evaluation completes, a message similar to the following appears:

DONE (t=5.47s).
 Average Precision  (AP) @[ IoU=0.50:0.95 | area=   all | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50      | area=   all | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.75      | area=   all | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area= small | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area=medium | maxDets=100 ] = 0.000
 Average Precision  (AP) @[ IoU=0.50:0.95 | area= large | maxDets=100 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets=  1 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets= 10 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=   all | maxDets=100 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area= small | maxDets=100 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area=medium | maxDets=100 ] = 0.000
 Average Recall     (AR) @[ IoU=0.50:0.95 | area= large | maxDets=100 ] = 0.000

You have now completed single-device training and evaluation. Use the following steps to delete the current single-device TPU resources.

Disconnect from the Compute Engine instance:
```
(vm)$ exit
```
Your prompt should now be username@projectname, showing you are in the Cloud Shell.
Delete the TPU resource.
```
$ gcloud compute tpus tpu-vm delete shapemask-tutorial \
    --zone=europe-west4-a
```
Command flag descriptions

zone

The zone where your Cloud TPU resided.

At this point, you can either conclude this tutorial and clean up, or you can continue and explore running the model on Cloud TPU Pods.

Scale your model with Cloud TPU Pods

Training your model on Cloud TPU Pods may require some changes to your training script. For information, see Training on TPU Pods.

TPU Pod training

Open a Cloud Shell window.

Open Cloud Shell
Create a variable for your project's ID.
```
export PROJECT_ID=project-id
```
Configure Google Cloud CLI to use the project where you want to create Cloud TPU.
```
gcloud config set project ${PROJECT_ID}
```
The first time you run this command in a new Cloud Shell VM, an Authorize Cloud Shell page is displayed. Click Authorize at the bottom of the page to allow gcloud to make Google Cloud API calls with your credentials.
Create a Service Account for the Cloud TPU project.

Service accounts allow the Cloud TPU service to access other Google Cloud services.
```
gcloud beta services identity create --service tpu.googleapis.com --project $PROJECT_ID
```
The command returns a Cloud TPU Service Account with following format:
```
service-PROJECT_NUMBER@cloud-tpu.iam.gserviceaccount.com
```
Create a Cloud Storage bucket using the following command or use an existing bucket.

Important: Set up your Cloud TPU resources and your Cloud Storage bucket in the same region and zone to reduce network latency and network costs. Cloud TPUs are located in specific zones, which are subdivisions within a region.
```
gcloud storage buckets create gs://bucket-name --project=${PROJECT_ID} --location=europe-west4
```
If you previously prepared the COCO dataset and moved it to your storage bucket, you can use it again for Pod training. If you have not yet prepared the COCO dataset, prepare it now and return here to set up the Pod training.
Launch a Cloud TPU Pod

This tutorial specifies a v3-32 Pod. For other Pod options, see TPU versions.

Note: If there is not enough capacity currently available to create the TPU Pod, you can queue your request using queued resources. Queued resources allow you to receive capacity once it becomes available. To request your Cloud TPU resources as queued resources, use the gcloud compute tpus queued-resources create command instead. For more information, see Manage Queued Resources.
```
$ gcloud compute tpus tpu-vm create shapemask-tutorial \
  --zone=europe-west4-a \
  --accelerator-type=v3-32 \
  --version=tpu-vm-tf-2.17.0-pod-pjrt
```
Command flag descriptions

zone

The zone where you plan to create your Cloud TPU.

accelerator-type

The accelerator type specifies the version and size of the Cloud TPU you want to create. For more information about supported accelerator types for each TPU version, see TPU versions.

version

The Cloud TPU software version.

Note: The first time you run gcloud on a project it takes about 5 minutes to perform startup tasks such as SSH key propagation and API turnup.
Note: If you have more than one project, you must specify the project ID with the --project flag.
Connect to the Compute Engine instance using SSH. When you are connected to the VM, your shell prompt changes from username@projectname to username@vm-name:
```
gcloud compute tpus tpu-vm ssh shapemask-tutorial --zone=europe-west4-a
```
Key Point: From this point on, a prefix of (vm) $ means you should run the command on the Compute Engine VM instance.

Install TensorFlow requirements.

(vm)$ pip3 install -r /usr/share/tpu/models/official/requirements.txt

The training script requires an extra package. Install it now:

(vm)$ pip3 install --user tensorflow-model-optimization>=0.1.3

Set up the following environment variables, replacing bucket-name with the name of your Cloud Storage bucket:
```
(vm)$ export STORAGE_BUCKET=gs://bucket-name
```
The training application expects your training data to be accessible in Cloud Storage. The training application also uses your Cloud Storage bucket to store checkpoints during training.

Update the required training variables.

(vm)$ export MODEL_DIR=${STORAGE_BUCKET}/shapemask-pods
(vm)$ export DATA_DIR=${STORAGE_BUCKET}/coco
(vm)$ export RESNET_CHECKPOINT=gs://cloud-tpu-checkpoints/retinanet/resnet50-checkpoint-2018-02-07
(vm)$ export TRAIN_FILE_PATTERN=${DATA_DIR}/train-*
(vm)$ export EVAL_FILE_PATTERN=${DATA_DIR}/val-*
(vm)$ export VAL_JSON_FILE=${DATA_DIR}/instances_val2017.json
(vm)$ export SHAPE_PRIOR_PATH=gs://cloud-tpu-checkpoints/shapemask/kmeans_class_priors_91x20x32x32.npy

Set some required environment variables:

(vm)$ export PYTHONPATH="/usr/share/tpu/models:${PYTHONPATH}"
(vm)$ export TPU_LOAD_LIBRARY=0

Change to directory that stores the model:

(vm)$ cd /usr/share/tpu/models/official/legacy/detection

Start the Pod training.

The sample training runs for 20 steps and takes approximately 10 minutes to complete on a v3-32 TPU node. To train to convergence takes about 11,250 steps and approximately 2 hours on a v3-32 TPU Pod.
```
(vm)$ python3 main.py \
 --strategy_type=tpu \
 --tpu=${TPU_NAME} \
 --model_dir=${MODEL_DIR} \
 --mode=train \
 --model=shapemask \
 --params_override="{train: { batch_size: 128, iterations_per_loop: 500, total_steps: 20, learning_rate: {'learning_rate_levels': [0.008, 0.0008], 'learning_rate_steps': [10000, 13000] }, checkpoint: { path: ${RESNET_CHECKPOINT}, prefix: resnet50/ }, train_file_pattern: ${TRAIN_FILE_PATTERN} }, eval: { val_json_file: ${VAL_JSON_FILE}, eval_file_pattern: ${EVAL_FILE_PATTERN}}, shapemask_head: {use_category_for_mask: true, shape_prior_path: ${SHAPE_PRIOR_PATH}} }"
```
Command flag descriptions

strategy_type

To train the Shapemask model on a TPU, you must set the distribution_strategy to tpu.

tpu

The name of the Cloud TPU. This is set using the TPU_NAME environment variable.

model_dir

The directory where checkpoints and summaries are stored during model training. If the folder is missing, the program creates one. When using a Cloud TPU, the model_dir must be a Cloud Storage path (gs://...). You can reuse an existing folder to load current checkpoint data and to store additional checkpoints as long as the previous checkpoints were created using a Cloud TPU of the same size and TensorFlow version.

mode

Set this to train to train the model or eval to evaluate the model.

params_override

A JSON string that overrides default script parameters. For more information on script parameters, see /usr/share/models/official/legacy/detection/main.py.

Clean up

To avoid incurring charges to your Google Cloud account for the resources used in this tutorial, either delete the project that contains the resources, or keep the project and delete the individual resources.

Disconnect from the Compute Engine instance, if you have not already done so:
```
(vm)$ exit
```
Your prompt should now be username@projectname, showing you are in the Cloud Shell.

Delete your Cloud TPU and Compute Engine resources.

$ gcloud compute tpus tpu-vm delete shapemask-tutorial \
--zone=europe-west4-a

Verify the resources have been deleted by running gcloud compute tpus tpu-vm list. The deletion might take several minutes. The output from the following command shouldn't include any of the TPU resources created in this tutorial:
```
$ gcloud compute tpus tpu-vm list --zone=europe-west4-a
```
Run the gcloud CLI as shown, replacing bucket-name with the name of the Cloud Storage bucket you created for this tutorial:

Caution: All training data will be lost when you delete your bucket, so only do this step when you are finished running the tutorial.
```
$ gcloud storage rm gs://bucket-name --recursive
```

What's next

Train with different image sizes

You can explore using a larger neural network (for example, ResNet-101 instead of ResNet-50). A larger input image and a more powerful neural network will yield a slower but more precise model.

Use a different basis

Alternatively, you can explore pre-training a ResNet model on your own dataset and using it as a basis for your ShapeMask model. With some more work, you can also swap in an alternative neural network in place of ResNet. Finally, if you are interested in implementing your own object detection models, this network may be a good basis for further experimentation.