[go-nuts] NewTicker leak

[Fabián Inostroza]

Hi,

I'm writing and application where I need to check for some condition and do 
something every 'x' < 'y' seconds. If the condition is not true after 'y' 
seconds I do something. Every time the condition checked every 'x' seconds 
is true I have to reset the 'y' timeout.

I wrote a test application based on code found in 
https://medium.com/@arpith/resetting-a-ticker-in-go-63858a2c17ec
package main

import "time"

// Ticker asdf
type Ticker struct {
    period time.Duration
    ticker time.Ticker
}

func createTicker(period time.Duration) *Ticker {
    return &Ticker{period, *time.NewTicker(period)}
}

func (t *Ticker) resetTicker() {
    t.ticker.Stop()
    t.ticker = *time.NewTicker(t.period)
}

type timers struct {
    ticker1 Ticker
    ticker2 Ticker
    done    chan bool
}

func (t *timers) work() {
    condition := true
    count := 0
    for {
        select {
        case <-t.ticker1.ticker.C:
            if condition {
                if count >= 5 {
                    count = 0
                    condition = false
                } else {
                    t.ticker2.resetTicker()
                    count++
                }
            }
        case <-t.ticker2.ticker.C:
            if count >= 2 {
                count = 0
                condition = true
            }
            count++
        case <-t.done:
            return
        }
    }
}

func createPeriodicTask() *timers {
    ticker1 := createTicker(time.Duration(5) * time.Second)
    ticker2 := createTicker(time.Duration(1) * time.Minute)
    quit := make(chan bool)

    timer := timers{*ticker1, *ticker2, quit}
    return &timer
}

func main() {
    timersArray := make([]*timers, 1000)

    for i := range timersArray {
        timer := createPeriodicTask()
        timersArray[i] = timer
        go timer.work()
    }

    //m := runtime.MemStats{}
    for {
        for i := range timersArray {
            select {
            case <-timersArray[i].done:
                break
            default:
                time.Sleep(time.Duration(2000) * time.Millisecond)
                //fmt.Println("Numero de goroutines existentes: ", 
runtime.NumGoroutine())
                //runtime.ReadMemStats(&m)
                //fmt.Printf("%+v\n", m)
            }
        }
    }
}


If I run this program for many hours the memory usage of the process 
steadily increases.

I changed the Ticker struct definition to use pointers to the 
time.newTicker and the problem is gone but I don't understand what was 
wrong with the first version, could somebody give me a hint?

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