Recently I was working with a group that computed user-defined attributes for each task (e.g. the start and stop time when running the task) and stored them in an external database. However, after #4107 we now have a TaskState object on both the worker and scheduler which could be used to store custom task-level information directly on the cluster.

For example, we could add a new TaskState.metadata mapping to both the scheduler and worker TaskState classes and synchronize them when Worker.send_task_state_to_scheduler is called. This would give users an option to store rich information relevant to their particular workloads

This seems like useful functionality to me and I wanted to see if other groups may also benefit from adding task-level metadata