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Load balancing ​

Load balancing is the principle of efficiently distributing tasks over resources to avoid overload.

Dedicated / central Load balancer

  • Runs in separate process
  • Shared by clients, for multiple services
  • Possible bottlenecks

Client-side Load balancer

  • Implemented/used as a library
  • Client decide which service instant to connect
  • Require registry to have an overview

Circuit breaker ​

The circuit breaker avoid requests overload of a service by cutting requests before it’s to late. The application won’t waste resources (RAM, CPU) on requests that will never return anyway

State

  • Closed: count the number of failed requests. Passed a certain threshold, state pass to open and rester after a certain amount of time
  • Open: requests are blocked. The state pass to half-open after some time or by sending request to himself as health check
  • Half-open: only some request pass. Switch to one or other state depending of amount of succeeded/failed requests

Scheduling ​