如何有效停止Gocron工作？

Question

I am doing something like this:

package main

import (
    "fmt"
    "time"

    "github.com/jasonlvhit/gocron"
)

func jobs(quit <-chan bool) {
    for {
        select {
        case <-quit:
            return
        default:
            //cron jobs
            g := gocron.NewScheduler()
            g.Every(1).Second().Do(stuff)
            <-g.Start()
        }
    }
}

func stuff() {
    fmt.Println("doing job")
}

func main() {
    q := make(chan bool)
    go jobs(q)
    time.Sleep(3 * time.Second)

 //to quit the goroutine
    q <- true    
    close(q)
    fmt.Println("main")
}

I'm trying to stop the gocrons by killing the goroutine by closing the channel but I'm not able to stop gocron jobs. I am getting output

            doing job
            doing job
            doing job
            doing job
            doing job
            doing job
            doing job
            .
            .

Instead of

            doing job
            doing job
            doing job
            main

What am I doing wrong? Is there any better solution to stop gocron jobs?

Answer 1

Your problem is in the select block here:

    select {
    case <-quit:
        return
    default:
        //cron jobs
        g := gocron.NewScheduler()
        g.Every(1).Second().Do(stuff)
        <-g.Start()
    }

This code says: select the case we can read from quit and exit, or do the default case.

Entering the default part of the case will block the goroutine on <-g.Start() until all the jobs are done. We have to wait here for the jobs to finish. While we are still waiting on <-g.Start() we do not consider the quit channel.

Instead do:

func jobs(quit <-chan bool) {
    for {
        //cron jobs
        g := gocron.NewScheduler()
        g.Every(1).Second().Do(stuff)

        select {
        case <-quit:
            // here we receive from quit and exit
            // if `g` has started, we may want to `g.Clear()`
            // or the scheduled jobs will continue, we will just not be waiting for them to finish.
            return
        case <-g.Start():
            // here we know all the jobs are done, and go round the loop again
        }
    }
}