func main() { c := make(chan int, 1000) var wg sync.WaitGroup wg.Add(100) for i := 0; i < 100; i++ { go func() { defer wg.Done() foo(c) }() } go func() { wg.Wait() close(c) }() sum := 0 for r := range c { sum += r } // fmt.Println(sum) } func foo_req(c chan int) error { r := rand.Int() for i := 0; i < r; i++ { c <- r } }

The provided code has several issues:

1. In the foo_req function (which calls foo in the code but is defined as foo_req), there is a write to the channel c in a loop from 0 to r, where r is a random number. This can lead to blocking if the channel buffer overflows, since the channel is buffered for 1000 elements, and r can be larger.

2. In the goroutine that runs foo, the parameter i is not passed, but this is not critical since i is not used inside.

3. The foo_req function does not return an error, although error is declared.

4. In main, there is correct waiting for all goroutines to finish via WaitGroup and closing the channel.

To avoid blocking, ensure that the number of elements sent to the channel does not exceed its buffer, or use non-blocking send or additional synchronization.

Example fix for the foo function:

func foo(c chan int) {
    r := rand.Intn(1000) // limit maximum
    for i := 0; i < r; i++ {
        c <- r
    }
}

Or use non-blocking send with select:

func foo(c chan int) {
    r := rand.Intn(1000)
    for i := 0; i < r; i++ {
        select {
        case c <- r:
        default:
            // channel is full, handle situation
        }
    }
}

Also, check that rand is initialized, and fix any inconsistencies in function names.