Elasticity, in this case, means both: 1) the ability for a job to continue after node failure (by running with fewer nodes and/or by incorporating a new host and transferring state to it); and 2) the ability to add/remove nodes dynamically due to resource availability changes or bottlenecks.
While this feature is still experimental, you can try it out on AWS EC2, with the instructions here. Additionally, the PyTorch distributed team is working closely with teams across AWS to support PyTorch Elastic training within services such as Amazon Sagemaker and Elastic Kubernetes Service (EKS). Look for additional updates in the near future.
New Classification Framework