Circuitbreaker not performing MaxRequests operations in Half-open state

[DaChartreux]

It is stated that

// MaxRequests is the maximum number of requests allowed to pass through
// when the CircuitBreaker is half-open.
// If MaxRequests is 0, the CircuitBreaker allows only 1 request.

Considering this, I assume that the circuit breaker will perform MaxRequests count of operations before opening? But it doesn't.

Here is a reproducible code

package main

import (
	"errors"
	"fmt"
	"github.com/sony/gobreaker"
	"time"
)

func main() {
	cb := gobreaker.NewCircuitBreaker(gobreaker.Settings{
		Name:          "sad",
		MaxRequests:   20,
		Interval:      time.Second * 10,
		Timeout:       time.Second * 1,
		ReadyToTrip: func(counts gobreaker.Counts) bool {
			failureRatio := float64(counts.TotalFailures) / float64(counts.Requests)
			if failureRatio > 0.7 {
				fmt.Printf("will trip? %+v\n", counts)
			}
			return counts.Requests >= 100 && failureRatio > 0.7
		},
		OnStateChange: func(name string, from gobreaker.State, to gobreaker.State) {
			fmt.Printf("Circuit breaker %v state change from %v to %v\n", name, from, to)
		},
	})

	for {
		cb.Execute(func() (interface{}, error) {
			return nil, fun()
		})
	}
}

func fun() error {
	fmt.Println("RUNNING")
	return errors.New("LMAO")
}

This prints...

RUNNING
will trip? {Requests:1 TotalSuccesses:0 TotalFailures:1 ConsecutiveSuccesses:0 ConsecutiveFailures:1}
RUNNING
will trip? {Requests:2 TotalSuccesses:0 TotalFailures:2 ConsecutiveSuccesses:0 ConsecutiveFailures:2}
RUNNING
will trip? {Requests:3 TotalSuccesses:0 TotalFailures:3 ConsecutiveSuccesses:0 ConsecutiveFailures:3}
RUNNING
will trip? {Requests:4 TotalSuccesses:0 TotalFailures:4 ConsecutiveSuccesses:0 ConsecutiveFailures:4}
RUNNING
will trip? {Requests:5 TotalSuccesses:0 TotalFailures:5 ConsecutiveSuccesses:0 ConsecutiveFailures:5}
RUNNING
will trip? {Requests:6 TotalSuccesses:0 TotalFailures:6 ConsecutiveSuccesses:0 ConsecutiveFailures:6}
RUNNING
will trip? {Requests:7 TotalSuccesses:0 TotalFailures:7 ConsecutiveSuccesses:0 ConsecutiveFailures:7}
RUNNING
will trip? {Requests:8 TotalSuccesses:0 TotalFailures:8 ConsecutiveSuccesses:0 ConsecutiveFailures:8}
RUNNING
will trip? {Requests:9 TotalSuccesses:0 TotalFailures:9 ConsecutiveSuccesses:0 ConsecutiveFailures:9}
RUNNING
will trip? {Requests:10 TotalSuccesses:0 TotalFailures:10 ConsecutiveSuccesses:0 ConsecutiveFailures:10}
RUNNING
will trip? {Requests:11 TotalSuccesses:0 TotalFailures:11 ConsecutiveSuccesses:0 ConsecutiveFailures:11}
RUNNING
will trip? {Requests:12 TotalSuccesses:0 TotalFailures:12 ConsecutiveSuccesses:0 ConsecutiveFailures:12}
RUNNING
will trip? {Requests:13 TotalSuccesses:0 TotalFailures:13 ConsecutiveSuccesses:0 ConsecutiveFailures:13}
RUNNING
will trip? {Requests:14 TotalSuccesses:0 TotalFailures:14 ConsecutiveSuccesses:0 ConsecutiveFailures:14}
RUNNING
will trip? {Requests:15 TotalSuccesses:0 TotalFailures:15 ConsecutiveSuccesses:0 ConsecutiveFailures:15}
RUNNING
will trip? {Requests:16 TotalSuccesses:0 TotalFailures:16 ConsecutiveSuccesses:0 ConsecutiveFailures:16}
RUNNING
will trip? {Requests:17 TotalSuccesses:0 TotalFailures:17 ConsecutiveSuccesses:0 ConsecutiveFailures:17}
RUNNING
will trip? {Requests:18 TotalSuccesses:0 TotalFailures:18 ConsecutiveSuccesses:0 ConsecutiveFailures:18}
RUNNING
will trip? {Requests:19 TotalSuccesses:0 TotalFailures:19 ConsecutiveSuccesses:0 ConsecutiveFailures:19}
RUNNING
will trip? {Requests:20 TotalSuccesses:0 TotalFailures:20 ConsecutiveSuccesses:0 ConsecutiveFailures:20}
RUNNING
will trip? {Requests:21 TotalSuccesses:0 TotalFailures:21 ConsecutiveSuccesses:0 ConsecutiveFailures:21}
RUNNING
will trip? {Requests:22 TotalSuccesses:0 TotalFailures:22 ConsecutiveSuccesses:0 ConsecutiveFailures:22}
RUNNING
will trip? {Requests:23 TotalSuccesses:0 TotalFailures:23 ConsecutiveSuccesses:0 ConsecutiveFailures:23}
RUNNING
will trip? {Requests:24 TotalSuccesses:0 TotalFailures:24 ConsecutiveSuccesses:0 ConsecutiveFailures:24}
RUNNING
will trip? {Requests:25 TotalSuccesses:0 TotalFailures:25 ConsecutiveSuccesses:0 ConsecutiveFailures:25}
RUNNING
will trip? {Requests:26 TotalSuccesses:0 TotalFailures:26 ConsecutiveSuccesses:0 ConsecutiveFailures:26}
RUNNING
will trip? {Requests:27 TotalSuccesses:0 TotalFailures:27 ConsecutiveSuccesses:0 ConsecutiveFailures:27}
RUNNING
will trip? {Requests:28 TotalSuccesses:0 TotalFailures:28 ConsecutiveSuccesses:0 ConsecutiveFailures:28}
RUNNING
will trip? {Requests:29 TotalSuccesses:0 TotalFailures:29 ConsecutiveSuccesses:0 ConsecutiveFailures:29}
RUNNING
will trip? {Requests:30 TotalSuccesses:0 TotalFailures:30 ConsecutiveSuccesses:0 ConsecutiveFailures:30}
RUNNING
will trip? {Requests:31 TotalSuccesses:0 TotalFailures:31 ConsecutiveSuccesses:0 ConsecutiveFailures:31}
RUNNING
will trip? {Requests:32 TotalSuccesses:0 TotalFailures:32 ConsecutiveSuccesses:0 ConsecutiveFailures:32}
RUNNING
will trip? {Requests:33 TotalSuccesses:0 TotalFailures:33 ConsecutiveSuccesses:0 ConsecutiveFailures:33}
RUNNING
will trip? {Requests:34 TotalSuccesses:0 TotalFailures:34 ConsecutiveSuccesses:0 ConsecutiveFailures:34}
RUNNING
will trip? {Requests:35 TotalSuccesses:0 TotalFailures:35 ConsecutiveSuccesses:0 ConsecutiveFailures:35}
RUNNING
will trip? {Requests:36 TotalSuccesses:0 TotalFailures:36 ConsecutiveSuccesses:0 ConsecutiveFailures:36}
RUNNING
will trip? {Requests:37 TotalSuccesses:0 TotalFailures:37 ConsecutiveSuccesses:0 ConsecutiveFailures:37}
RUNNING
will trip? {Requests:38 TotalSuccesses:0 TotalFailures:38 ConsecutiveSuccesses:0 ConsecutiveFailures:38}
RUNNING
will trip? {Requests:39 TotalSuccesses:0 TotalFailures:39 ConsecutiveSuccesses:0 ConsecutiveFailures:39}
RUNNING
will trip? {Requests:40 TotalSuccesses:0 TotalFailures:40 ConsecutiveSuccesses:0 ConsecutiveFailures:40}
RUNNING
will trip? {Requests:41 TotalSuccesses:0 TotalFailures:41 ConsecutiveSuccesses:0 ConsecutiveFailures:41}
RUNNING
will trip? {Requests:42 TotalSuccesses:0 TotalFailures:42 ConsecutiveSuccesses:0 ConsecutiveFailures:42}
RUNNING
will trip? {Requests:43 TotalSuccesses:0 TotalFailures:43 ConsecutiveSuccesses:0 ConsecutiveFailures:43}
RUNNING
will trip? {Requests:44 TotalSuccesses:0 TotalFailures:44 ConsecutiveSuccesses:0 ConsecutiveFailures:44}
RUNNING
will trip? {Requests:45 TotalSuccesses:0 TotalFailures:45 ConsecutiveSuccesses:0 ConsecutiveFailures:45}
RUNNING
will trip? {Requests:46 TotalSuccesses:0 TotalFailures:46 ConsecutiveSuccesses:0 ConsecutiveFailures:46}
RUNNING
will trip? {Requests:47 TotalSuccesses:0 TotalFailures:47 ConsecutiveSuccesses:0 ConsecutiveFailures:47}
RUNNING
will trip? {Requests:48 TotalSuccesses:0 TotalFailures:48 ConsecutiveSuccesses:0 ConsecutiveFailures:48}
RUNNING
will trip? {Requests:49 TotalSuccesses:0 TotalFailures:49 ConsecutiveSuccesses:0 ConsecutiveFailures:49}
RUNNING
will trip? {Requests:50 TotalSuccesses:0 TotalFailures:50 ConsecutiveSuccesses:0 ConsecutiveFailures:50}
RUNNING
will trip? {Requests:51 TotalSuccesses:0 TotalFailures:51 ConsecutiveSuccesses:0 ConsecutiveFailures:51}
RUNNING
will trip? {Requests:52 TotalSuccesses:0 TotalFailures:52 ConsecutiveSuccesses:0 ConsecutiveFailures:52}
RUNNING
will trip? {Requests:53 TotalSuccesses:0 TotalFailures:53 ConsecutiveSuccesses:0 ConsecutiveFailures:53}
RUNNING
will trip? {Requests:54 TotalSuccesses:0 TotalFailures:54 ConsecutiveSuccesses:0 ConsecutiveFailures:54}
RUNNING
will trip? {Requests:55 TotalSuccesses:0 TotalFailures:55 ConsecutiveSuccesses:0 ConsecutiveFailures:55}
RUNNING
will trip? {Requests:56 TotalSuccesses:0 TotalFailures:56 ConsecutiveSuccesses:0 ConsecutiveFailures:56}
RUNNING
will trip? {Requests:57 TotalSuccesses:0 TotalFailures:57 ConsecutiveSuccesses:0 ConsecutiveFailures:57}
RUNNING
will trip? {Requests:58 TotalSuccesses:0 TotalFailures:58 ConsecutiveSuccesses:0 ConsecutiveFailures:58}
RUNNING
will trip? {Requests:59 TotalSuccesses:0 TotalFailures:59 ConsecutiveSuccesses:0 ConsecutiveFailures:59}
RUNNING
will trip? {Requests:60 TotalSuccesses:0 TotalFailures:60 ConsecutiveSuccesses:0 ConsecutiveFailures:60}
RUNNING
will trip? {Requests:61 TotalSuccesses:0 TotalFailures:61 ConsecutiveSuccesses:0 ConsecutiveFailures:61}
RUNNING
will trip? {Requests:62 TotalSuccesses:0 TotalFailures:62 ConsecutiveSuccesses:0 ConsecutiveFailures:62}
RUNNING
will trip? {Requests:63 TotalSuccesses:0 TotalFailures:63 ConsecutiveSuccesses:0 ConsecutiveFailures:63}
RUNNING
will trip? {Requests:64 TotalSuccesses:0 TotalFailures:64 ConsecutiveSuccesses:0 ConsecutiveFailures:64}
RUNNING
will trip? {Requests:65 TotalSuccesses:0 TotalFailures:65 ConsecutiveSuccesses:0 ConsecutiveFailures:65}
RUNNING
will trip? {Requests:66 TotalSuccesses:0 TotalFailures:66 ConsecutiveSuccesses:0 ConsecutiveFailures:66}
RUNNING
will trip? {Requests:67 TotalSuccesses:0 TotalFailures:67 ConsecutiveSuccesses:0 ConsecutiveFailures:67}
RUNNING
will trip? {Requests:68 TotalSuccesses:0 TotalFailures:68 ConsecutiveSuccesses:0 ConsecutiveFailures:68}
RUNNING
will trip? {Requests:69 TotalSuccesses:0 TotalFailures:69 ConsecutiveSuccesses:0 ConsecutiveFailures:69}
RUNNING
will trip? {Requests:70 TotalSuccesses:0 TotalFailures:70 ConsecutiveSuccesses:0 ConsecutiveFailures:70}
RUNNING
will trip? {Requests:71 TotalSuccesses:0 TotalFailures:71 ConsecutiveSuccesses:0 ConsecutiveFailures:71}
RUNNING
will trip? {Requests:72 TotalSuccesses:0 TotalFailures:72 ConsecutiveSuccesses:0 ConsecutiveFailures:72}
RUNNING
will trip? {Requests:73 TotalSuccesses:0 TotalFailures:73 ConsecutiveSuccesses:0 ConsecutiveFailures:73}
RUNNING
will trip? {Requests:74 TotalSuccesses:0 TotalFailures:74 ConsecutiveSuccesses:0 ConsecutiveFailures:74}
RUNNING
will trip? {Requests:75 TotalSuccesses:0 TotalFailures:75 ConsecutiveSuccesses:0 ConsecutiveFailures:75}
RUNNING
will trip? {Requests:76 TotalSuccesses:0 TotalFailures:76 ConsecutiveSuccesses:0 ConsecutiveFailures:76}
RUNNING
will trip? {Requests:77 TotalSuccesses:0 TotalFailures:77 ConsecutiveSuccesses:0 ConsecutiveFailures:77}
RUNNING
will trip? {Requests:78 TotalSuccesses:0 TotalFailures:78 ConsecutiveSuccesses:0 ConsecutiveFailures:78}
RUNNING
will trip? {Requests:79 TotalSuccesses:0 TotalFailures:79 ConsecutiveSuccesses:0 ConsecutiveFailures:79}
RUNNING
will trip? {Requests:80 TotalSuccesses:0 TotalFailures:80 ConsecutiveSuccesses:0 ConsecutiveFailures:80}
RUNNING
will trip? {Requests:81 TotalSuccesses:0 TotalFailures:81 ConsecutiveSuccesses:0 ConsecutiveFailures:81}
RUNNING
will trip? {Requests:82 TotalSuccesses:0 TotalFailures:82 ConsecutiveSuccesses:0 ConsecutiveFailures:82}
RUNNING
will trip? {Requests:83 TotalSuccesses:0 TotalFailures:83 ConsecutiveSuccesses:0 ConsecutiveFailures:83}
RUNNING
will trip? {Requests:84 TotalSuccesses:0 TotalFailures:84 ConsecutiveSuccesses:0 ConsecutiveFailures:84}
RUNNING
will trip? {Requests:85 TotalSuccesses:0 TotalFailures:85 ConsecutiveSuccesses:0 ConsecutiveFailures:85}
RUNNING
will trip? {Requests:86 TotalSuccesses:0 TotalFailures:86 ConsecutiveSuccesses:0 ConsecutiveFailures:86}
RUNNING
will trip? {Requests:87 TotalSuccesses:0 TotalFailures:87 ConsecutiveSuccesses:0 ConsecutiveFailures:87}
RUNNING
will trip? {Requests:88 TotalSuccesses:0 TotalFailures:88 ConsecutiveSuccesses:0 ConsecutiveFailures:88}
RUNNING
will trip? {Requests:89 TotalSuccesses:0 TotalFailures:89 ConsecutiveSuccesses:0 ConsecutiveFailures:89}
RUNNING
will trip? {Requests:90 TotalSuccesses:0 TotalFailures:90 ConsecutiveSuccesses:0 ConsecutiveFailures:90}
RUNNING
will trip? {Requests:91 TotalSuccesses:0 TotalFailures:91 ConsecutiveSuccesses:0 ConsecutiveFailures:91}
RUNNING
will trip? {Requests:92 TotalSuccesses:0 TotalFailures:92 ConsecutiveSuccesses:0 ConsecutiveFailures:92}
RUNNING
will trip? {Requests:93 TotalSuccesses:0 TotalFailures:93 ConsecutiveSuccesses:0 ConsecutiveFailures:93}
RUNNING
will trip? {Requests:94 TotalSuccesses:0 TotalFailures:94 ConsecutiveSuccesses:0 ConsecutiveFailures:94}
RUNNING
will trip? {Requests:95 TotalSuccesses:0 TotalFailures:95 ConsecutiveSuccesses:0 ConsecutiveFailures:95}
RUNNING
will trip? {Requests:96 TotalSuccesses:0 TotalFailures:96 ConsecutiveSuccesses:0 ConsecutiveFailures:96}
RUNNING
will trip? {Requests:97 TotalSuccesses:0 TotalFailures:97 ConsecutiveSuccesses:0 ConsecutiveFailures:97}
RUNNING
will trip? {Requests:98 TotalSuccesses:0 TotalFailures:98 ConsecutiveSuccesses:0 ConsecutiveFailures:98}
RUNNING
will trip? {Requests:99 TotalSuccesses:0 TotalFailures:99 ConsecutiveSuccesses:0 ConsecutiveFailures:99}
RUNNING
will trip? {Requests:100 TotalSuccesses:0 TotalFailures:100 ConsecutiveSuccesses:0 ConsecutiveFailures:100}
Circuit breaker sad state change from closed to open
Circuit breaker sad state change from open to half-open
RUNNING
Circuit breaker sad state change from half-open to open
Circuit breaker sad state change from open to half-open
RUNNING
Circuit breaker sad state change from half-open to open
^C

Why is it executing only once in half-open state?

[hankji]

Same problem.
because all request must be success then state will be open in the interval duration.
look like it's a bug
Does anyone still maintain this repository?

[DaChartreux]

According to "Release It! Design and Deploy Production-ready Software" book by Michael T. Nygard,

We make a single call in half open mode, if that fails, circuit breaker opens, else it closes.
For me, this was new coming from resilience4j

[plabondutta]

@DaChartreux
But then again, if that is so, the MaxRequests settings shouldn't be present at all. This just doesn't make any sense.

[YoshiyukiMineo]

This behavior is following the specification:

If any request fails, the circuit breaker assumes that the fault is still present so it reverts back to the Open state
https://learn.microsoft.com/en-us/previous-versions/msp-n-p/dn589784(v=pandp.10)?redirectedfrom=MSDN

If any operation fails even once, it will move to the Open state.

A limited number of requests from the application are allowed

A limited number (MaxRequests) of requests are allowed at most.