如何在Go中并行调用函数

Question

I am trying to run a function in parallel.... when I do it

func runParallel() {
    var out [5]chan string
    for i := range out {
        out[i] = make(chan string)
    }
    for j:=0; j<2; j++ {
        fmt.Println("
Starting: ", j)
        go func() {
            out[0] <- f3(4)
        }()

        fmt.Println(<-out[0])
    }
}

func main() {    
    runParallel()
}

I see that function gets called serially one after the other... but when i do..

func runParallel() {
    var out [5]chan string
    for i := range out {
        out[i] = make(chan string)
    }

    fmt.Println("
Starting: ", j)
    go func() {
        out[0] <- f3(4)
    }()
    go func() {
        out[0] <- f3(4)
    }()

    fmt.Println(<-out[0])
}

func main() {    
    runParallel()
}

The function gets called parallel.

I need to get the function called parallel in a for loop, Please help.

Answer 1

Keep in mind that goroutines provide concurrency, and concurrency is not parallelism.

The problem in your first example is that you're reading from the unbuffered channel inside the for loop so the write that's happening in the goroutine is serialized waiting for the read. Move the read outside of the for loop, and/or put the read in it's own goroutine and you may see more parallelization.