LoadBalancing

All Balancers <<<<<<<<<<<<<

size A gauge of the number of nodes being balanced across.

available A gauge of the number of available nodes as seen by the load balancer. These nodes are ready to receive traffic.

busy A gauge of the number of busy nodes as seen by the load balancer. These nodes are current unavailable for service.

closed A gauge of the number of closed nodes as seen by the load balancer. These nodes will never be available for service.

load A gauge of the total load over all nodes being balanced across.

meanweight verbosity:debug A gauge tracking the arithmetic mean of the weights of the endpoints being load-balanced across.

num_weight_classes The number of groups (or classes) of weights in the load balancer. Each class gets a fresh instance of the client's load balancer and receives traffic proportional to its weight.

busy_weight_classes A counter of the number of times a weight class in the loadbalancer was found busy or closed.

adds A counter of the number of hosts added to the loadbalancer.

removes A counter of the number of hosts removed from the loadbalancer.

rebuilds A counter of the number of times the loadbalancer rebuilds its state (triggered by either an underlying namer or failing nodes).

updates A counter of the number of times the underlying namer triggers the loadbalancer to rebuild its state (e.g., because the server set has changed). Note that these kind of events are usually collapsed so the actual number of rebuilds is usually less than the number of updates.

panicked A counter of the number of times a balancer enters panic mode. The estimated portion of unhealthy nodes (status is not Status.Open) in the balancer exceeded the allowable threshold in com.twitter.finagle.loadbalancer.PanicMode. When this occurs, a non-open node may be selected for that request.

algorithm/{type} A gauge exported with the name of the algorithm used for load balancing.

Aperture Based Load Balancers <<<<<<<<<<<<<<<<<<<<<<<<<<<<<

logical_aperture A gauge of the width of the window over which endpoints are load-balanced. This is primarily an accounting mechanism and for a true representation of the number of endpoints the client is talking to see physical_aperture.

physical_aperture When using deterministic aperture (i.e. useDeterministicOrdering is set), the width of the window over which endpoints are load-balanced may be wider than the logical_aperture gauge. The physical_aperture represents this value.

use_deterministic_ordering 1 if the Aperture implementation uses deterministic ordering 0, otherwise.

vector_hash A gauge of the hash of the distributors serverset vector with range from [Int.MinValue, Int.MaxValue]. It is useful for identifying inconsistencies in the serverset observed by different instances of the same client since inconsistencies will result in very different values of vector_hash. This information is useful for identifying load banding issues when using the deterministic aperture load balancer which requires a consistent view of the backends to operate correctly.

coordinate_updates A counter of the number of times the Aperture implementation receives updates from the ProcessCoordinate process global.

expired A counter of the number of endpoints which have been closed because they have fallen out of the aperture window and become idle.