ResilienceMechanisms

Supported Resilience Mechanisms

Timeout

MiSim enforces a timeout of 8 STU.
It is currently not modifiable outside the code.

Retry

A strategic instance owned pattern that resents failed requests after a short delay.

JSON Type Names

• "retry"

Properties

Property	Description	Default
maxTries	The maximum number of retries.	5

Strategies

• "linear"
• "exponential" / "exp"
• "jittering"
• "jittering_linear"

All with the following properties:

Property	Description	Default
base	Multiplication base of the approach.	3
baseBackoff	Base back off value for the first attempt.	0.010
maxBackoff	Maximum Back off	1

Example

{
    "type": "retry",
    "config": {
        "maxTries": 3
    }
    "strategy": {
        "type": "jittering",
        "config": {
            "baseBackoff": 0.050,
            "maxBackoff": 2,
            "base": 2.25
        }
}

Circuit Breaker

An instance owned pattern that detects failing connections and employs a fail-fast strategy. Creates a circuit breaker for each target service independently.

JSON Type Names

• "circuitbreaker"

Properties

Property	Description	Default
requestVolumeThreshold	Maximum number of allowed concurrent connections.	Integer.MAX_VALUE
threshold	Failure rate threshold at which the breaker should open.	Double.POSITIVE_INFINITY
rollingWindow	Time window over which the failure rate should be calculated.	20 STU
sleepWindow	Time to wait until switching from OPEN to HALF-OPEN state.	0.5 STU

Example

{
  "type": "circuitbreaker",
  "config": {
    "threshold": 0.5,
    "rollingWindow": 10,
    "sleepWindow": 10.1
  }
}

Load Balancer

A strategic service owned pattern that distributes requests to multiple target instances. Every service must have a load balancer. If none is provided specifically a random strategy is used.

Strategies

Strategy	Description
random	Randomly selects a target instance.
round_robin	Selects the next target instance in a round-robin fashion.
round_robin_fast	Selects the next target instance in a round-robin fashion. It is not as fair as an actual round_robin, but slightly faster.
utilization	Selects the target instance with the lowest current relative utilization.

Example

{//In Service description
    ...
    "loadbalancer_strategy" : "round_robin",
    ...
}