Utility

ray.util.ActorPool	Utility class to operate on a fixed pool of actors.
ray.util.queue.Queue	A first-in, first-out queue implementation on Ray.
ray.nodes	Get a list of the nodes in the cluster (for debugging only).
ray.cluster_resources	Get the current total cluster resources.
ray.available_resources	Get the current available cluster resources.

Custom Metrics

ray.util.metrics.Counter	A cumulative metric that is monotonically increasing.
ray.util.metrics.Gauge	Gauges keep the last recorded value and drop everything before.
ray.util.metrics.Histogram	Tracks the size and number of events in buckets.

Debugging

ray.util.rpdb.set_trace	Interrupt the flow of the program and drop into the Ray debugger.
ray.util.inspect_serializability	Identifies what objects are preventing serialization.
ray.timeline	Return a list of profiling events that can viewed as a timeline.