Getting error "expected ';', found 'go'syntax" while trying to run a function in separate goroutine

Question

This is the code that I am trying to write ->

total ,err := go buildRepository.CountBuildScreenshots(buildId, OrgId, userID)
            if err!=nil {
                fmt.Println(err)
            }

Count Build Screenshots return an integer and an error.

My use case is that I have multiple builds for which I want to run this function. This function is computationally expensive and takes 5 seconds for computing for a single build. Hence I wanted to use wait Groups for the same.

for i := 0; i < len(builds); i++ {
            buildId := builds[i].BuildId
            buildRepository := NewBuildRepository(database.GetReadLTMSConn())
            total ,err := go (buildRepository.CountBuildScreenshots(buildId, OrgId, userID))
            if err!=nil {
                fmt.Println(err)
            }
            (builds[i]).TotalScreenshots = total
            
        }

Answer 1

I would wrap your function in a function that doesn't return anything but writes to a channel. Then you can read from that channel an wait for all results.

I am wrapping the loop in another goroutine to be able to close the channel after all are done writing to it.

type result struct {
    Count int
    Err   error
}

func main() {
    // the channel for the results
    c := make(chan result)
    
    // the top level goroutine waits for all
    // spawned goroutines to be done and closes the channel
    go func(c chan result) {
        // waitgroup is used to wait
        wg := &sync.WaitGroup{}

       // kick of the long running functions concurrently
       // in they own goroutine
        for i := 0; i < 10; i++ {
            wg.Add(1)
            go func(c chan result) {
                defer wg.Done()
                total, err = count()
                // write the results to the channel
                c <- result{total, err}
            }(c)
        }

        // wait until all are done
        wg.Wait()
        // important, close the channel
        close(c)
    }(c)
    

    // range over the results as they are coming in
    // until the channel is closed
    for r := range c {
        if r.Err != nil {
            fmt.Println(r.Err)
        } else {
            fmt.Println(r.Count)
        }
    }

}

// simulate a longer running function
func count() (int, error) {
    r := rand.Intn(10)
    time.Sleep(time.Duration(r) * time.Second)
    return 1, nil
}