shed is a Go and Ruby library implementing cross-service timeout/deadline
propagation and load shedding.
timeout/deadline propagation means advertising the client-side timeout for HTTP
requests. shed uses the X-Client-Timeout-Ms header to do this.
load shedding means dropping requests early when under load in order to free up resources. This can be done throughout the lifetime of the request, or before processing the request (e.g. if the request has been queued for longer than its client timeout).
Uncontrolled performance degradation of a service can quickly lead to resource exhaustion and cascading failures. Client progations and load-shedding along with other techniques (such as setting appropriate timeouts, retries, circuit breakers, etc.) can improve the manner in which your service fail under load.
Propagating client timeouts and shedding requests based on this allows your services to make more informed decisions about which requests are still worth processing, saving your limited and already over-utilised resources for requests that are still meaningful to process. This avoid wasted resources, improves availability under load, and speeds up recovery times by controlling request queueing.
In experiment run in CGA1123/loadshedding-experiment-ruby load-shedding across a single service hop with client timeout propagation improved availability of services by a factor of 10 under load.