Using Gin gonic and some scheduler in Golang

Question

I have some REST service in Gin Gonic, and I need to do some job every 5 seconds using some scheduler. I've tried rakanalh and gocron but it seems that every code written after initializing crons or gin routes will not execute.

func main() {
    settings.AppSettings = settings.ReadSettings()

    db.InitOracleDataBase()
    OracleEnv, OracleSrv, OracleSes := db.GetOracleDB()
    defer OracleEnv.Close()
    defer OracleSrv.Close()
    defer OracleSes.Close()

    routes.Init()


    gocron.Every(5).Seconds().Do(prOk)
    <-gocron.Start()


}

prOk just prints OK, and it never will be executed, until I comment routes.init(). How it's possible to run both cron and gin routes concurrently?

score 7 · Accepted Answer · answered Oct 09 '18 at 18:36

You need to execute the gocron inside a goroutine, since the main goroutine will block (I guess routes.Init() starts an HTTP server too?)

func main() {
    settings.AppSettings = settings.ReadSettings()

    db.InitOracleDataBase()
    OracleEnv, OracleSrv, OracleSes := db.GetOracleDB()
    defer OracleEnv.Close()
    defer OracleSrv.Close()
    defer OracleSes.Close()

    go func() {
        gocron.Every(5).Seconds().Do(prOk)
        <-gocron.Start()
    }()

    routes.Init()
}

score 5 · Answer 2 · answered Oct 09 '18 at 17:13

I am doing something similar, where I cache some API results and refresh cache every few seconds. I do not use anything beyond the standard library though. Here is some sample code.

func UpdateCache() {
    var lock sync.Mutex
    timer1 := time.NewTicker(time.Second * 10) 
    defer timer1.Stop()
    timer2 := time.NewTicker(time.Second * 5) 
    defer timer2.Stop()
    for {
        /* run forever */
        select {
        case <-timer1.C:
            go func() {
                lock.Lock()
                defer lock.Unlock()
                /* do things I need done every 10 seconds */
            }()
        case <-timer2.C:
            go func() {
                lock.Lock()
                defer lock.Unlock()
                /* do things I need done every 5 seconds */
            }()
        }
    }
}

And in the main() I have

go UpdateCache()
router := gin.Default()
/* setup all the routes */
listen := os.Getenv("SERVICE_ADDR")
router.Run(listen)

I think the problem you are running into is that you start running your routes in routes.Init() and it blocks and never gets to your cron setup.

Using Gin gonic and some scheduler in Golang

2 Answers2