聊聊dubbo-go的DefaultHealthChecker
序
本文主要研究一下dubbo-go的DefaultHealthChecker
DefaultHealthChecker
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
func init() {
extension.SethealthChecker(constant.DEFAULT_HEALTH_CHECKER, NewDefaultHealthChecker)
}
// DefaultHealthChecker is the default implementation of HealthChecker, which determines the health status of
// the invoker based on the number of successive bad request and the current active request.
type DefaultHealthChecker struct {
// the limit of outstanding request
outStandingRequestConutLimit int32
// the threshold of successive-failure-request
requestSuccessiveFailureThreshold int32
// value of circuit-tripped timeout factor
circuitTrippedTimeoutFactor int32
}
- DefaultHealthChecker定义了outStandingRequestConutLimit、requestSuccessiveFailureThreshold、circuitTrippedTimeoutFactor属性
NewDefaultHealthChecker
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
// NewDefaultHealthChecker constructs a new DefaultHealthChecker based on the url
func NewDefaultHealthChecker(url *common.URL) router.HealthChecker {
return &DefaultHealthChecker{
outStandingRequestConutLimit: int32(url.GetParamInt(constant.OUTSTANDING_REQUEST_COUNT_LIMIT_KEY, math.MaxInt32)),
requestSuccessiveFailureThreshold: int32(url.GetParamInt(constant.SUCCESSIVE_FAILED_REQUEST_THRESHOLD_KEY, constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF)),
circuitTrippedTimeoutFactor: int32(url.GetParamInt(constant.CIRCUIT_TRIPPED_TIMEOUT_FACTOR_KEY, constant.DEFAULT_CIRCUIT_TRIPPED_TIMEOUT_FACTOR)),
}
}
- NewDefaultHealthChecker实例化DefaultHealthChecker
IsHealthy
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
// IsHealthy evaluates the healthy state on the given Invoker based on the number of successive bad request
// and the current active request
func (c *DefaultHealthChecker) IsHealthy(invoker protocol.Invoker) bool {
urlStatus := protocol.GetURLStatus(invoker.GetUrl())
if c.isCircuitBreakerTripped(urlStatus) || urlStatus.GetActive() > c.GetOutStandingRequestConutLimit() {
logger.Debugf("Invoker [%s] is currently in circuitbreaker tripped state", invoker.GetUrl().Key())
return false
}
return true
}
- IsHealthy方法通过protocol.GetURLStatus(invoker.GetUrl())获取urlStatus,之后根据c.isCircuitBreakerTripped(urlStatus)或者
urlStatus.GetActive() > c.GetOutStandingRequestConutLimit()
判断是否处于circuitbreaker tripped状态
isCircuitBreakerTripped
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
// isCircuitBreakerTripped determine whether the invoker is in the tripped state by the number of successive bad request
func (c *DefaultHealthChecker) isCircuitBreakerTripped(status *protocol.RPCStatus) bool {
circuitBreakerTimeout := c.getCircuitBreakerTimeout(status)
currentTime := protocol.CurrentTimeMillis()
if circuitBreakerTimeout <= 0 {
return false
}
return circuitBreakerTimeout > currentTime
}
- isCircuitBreakerTripped方法通过c.getCircuitBreakerTimeout(status)获取circuitBreakerTimeout,若circuitBreakerTimeout小于等于0返回false,否则判断circuitBreakerTimeout是否大于currentTime
getCircuitBreakerTimeout
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
// getCircuitBreakerTimeout get the timestamp recovered from tripped state, the unit is millisecond
func (c *DefaultHealthChecker) getCircuitBreakerTimeout(status *protocol.RPCStatus) int64 {
sleepWindow := c.getCircuitBreakerSleepWindowTime(status)
if sleepWindow <= 0 {
return 0
}
return status.GetLastRequestFailedTimestamp() + sleepWindow
}
- getCircuitBreakerTimeout方法先获取sleepWindow,若sleepWindow小于等于0则返回0,否则返回status.GetLastRequestFailedTimestamp() + sleepWindow
getCircuitBreakerSleepWindowTime
dubbo-go-v1.4.2/cluster/router/healthcheck/default_health_check.go
// getCircuitBreakerSleepWindowTime get the sleep window time of invoker, the unit is millisecond
func (c *DefaultHealthChecker) getCircuitBreakerSleepWindowTime(status *protocol.RPCStatus) int64 {
successiveFailureCount := status.GetSuccessiveRequestFailureCount()
diff := successiveFailureCount - c.GetRequestSuccessiveFailureThreshold()
if diff < 0 {
return 0
} else if diff > constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF {
diff = constant.DEFAULT_SUCCESSIVE_FAILED_REQUEST_MAX_DIFF
}
sleepWindow := (1 << diff) * c.GetCircuitTrippedTimeoutFactor()
if sleepWindow > constant.MAX_CIRCUIT_TRIPPED_TIMEOUT_IN_MS {
sleepWindow = constant.MAX_CIRCUIT_TRIPPED_TIMEOUT_IN_MS
}
return int64(sleepWindow)
}
- getCircuitBreakerSleepWindowTime方法通过对比status.GetSuccessiveRequestFailureCount()及c.GetRequestSuccessiveFailureThreshold()计算diff,进而根据c.GetCircuitTrippedTimeoutFactor()计算sleepWindow
小结
DefaultHealthChecker定义了outStandingRequestConutLimit、requestSuccessiveFailureThreshold、circuitTrippedTimeoutFactor属性;IsHealthy方法通过protocol.GetURLStatus(invoker.GetUrl())获取urlStatus,之后根据c.isCircuitBreakerTripped(urlStatus)或者urlStatus.GetActive() > c.GetOutStandingRequestConutLimit()
判断是否处于circuitbreaker tripped状态
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