go - How to cancel goroutines after certain amount of time

Question

I am making a load testing tool that makes multiple HTTP calls in goroutines, and it works, but now I am trying to allow it to run for only a specified duration.

How can I cancel the goroutines when the sleep has finished?

What I am currently attempting to do is to make a goroutine that does time.Sleep() for the specified duration, and when that is finished it will broadcast a message to the channel.

In my infinite loop, I listen for the message in the switch statement, and when it is there I return. This works just as I want it to.

The problem is, the goroutines from the go httpPost() line will continue making HTTP calls. I even attempt to pass the channel into that function and listen for the same CALL_TIME_RAN_OUT message there as well, but for whatever reason when I do that the goroutines only run once and then immediately return, as opposed to waiting for the message to be broadcasted by the end of the Sleep.

Does anyone know a better approach I can take? This doesn't seem to be working.

Here's the code (removed irrelevant parts):

func attack(cfg AttackConfig) {
    // some code ...

    var ar attackResponse
    ch := make(chan uint8, 8)

    go func() {
        time.Sleep(cfg.Duration * time.Second)
        ch <- CALL_TIME_RAN_OUT
    }()

    for {
        if atomic.LoadInt32(&currConnections) < atomic.LoadInt32(&maxConnections) - 1 {
            go httpPost(cfg, &ar, ch)
        }

        switch <-ch {
        // some other cases ...
        case CALL_TIME_RAN_OUT:
            fmt.Printf("%d seconds have elapsed. Shutting down!", cfg.Duration)
            return
        }
    }
}

func httpPost(cfg AttackConfig, a *attackResponse, ch chan uint8) {
    // some code here to create HTTP client ...

    for {
        // some code to make HTTP call ...

        switch <-ch {
        case CALL_TIME_RAN_OUT:
            return
        }
    }
}

Answer 1

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