Q:

How to repeat the function N times per second?

How to repeat the function N times per second in Go?
I can:
N := 30 //Repeat 30 times per second
for {
    //Do something
    time.Sleep(time.Second * time.Duration(N))
}

But that just makes the intervals between repetitions

A:

There are two options, neither will get you a guaranteed x times per second.

Set N not to 30 but 1/30. Thus the sleep will be for 1/30th of a second.
Have an internal for-loop that loops 30 times and executes your 'do something', and then on exit you hit the statement that sleeps for a second.

Option One:
N := 30 //Repeat 30 times per second
for {
    //Do something
    time.Sleep(time.Duration(1e9 / N))  //time.second constant unnecessary (see kostya comments)
}

Option Two:
N := 1  //Sleep duration of one second
for {
    for i := 1;  i<=30; i++ {
        //Do something
    }
    time.Sleep(time.Second * time.Duration(N))
}

Note that in option two, everything happens all at once, and then you wait a second. The first option will space out the do something across the second. Because of timing in computers this won't be precise: sleep cannot guarantee it will wake up precisely when you expect.

A:

You can use a time.Ticker to handle all the book-keeping for you. The only "issue" is that if your operation takes longer than expected you'll loose ticks (and thus run fewer than N per second).
func doSomething() {
    const N = 30
    ticker := time.NewTicker(time.Second / N)
    for range ticker.C {
        fmt.Println("Do anything that takes no longer than 1/Nth of a second")
    }
}

https://play.golang.org/p/Gq-tWMvxIk

