Breaking Changes

• The timeout argument of ray.wait now uses seconds instead of milliseconds. #3706

Core

• Limit default redis max memory to 10GB. #3630
• Define a Node class to manage Ray processes. #3733
• Garbage collection of actor dummy objects. #3593
• Split profile table among many keys in the GCS. #3676
• Automatically try to figure out the memory limit in a docker container. #3605
• Improve multi-threading support. #3672
• Push a warning to all users when large number of workers have been started. #3645
• Refactor code ray.ObjectID code. #3674

Tune

• Change log handling for Tune. #3661
• Tune now supports resuming from cluster failure. #3309, #3725, #3657, #3681
• Support Configuration Merging for Suggestion Algorithms. #3584
• Support nested PBT mutations. #3455

RLlib

• Add starcraft multiagent env as example. #3542
• Allow development without needing to compile Ray. #3623
• Documentation for I/O API and multi-agent improvements. #3650
• Export policy model checkpoint. #3637
• Refactor PyTorch custom model support. #3634

Autoscaler

• Add an initial_workers option. #3530
• Add kill and get IP commands to CLI for testing. #3731
• GCP allow manual network configuration. #3748

Known Issues:

• Object broadcasts on large clusters are inefficient. #2945