Go Concurrency Using closures with goroutines in a loop
Example
When in a loop, the loop variable (val) in the following example is a single variable that changes value as it goes over the loop. Therefore one must do the following to actually pass each val of values to the goroutine:
for val := range values {
go func(val interface{}) {
fmt.Println(val)
}(val)
}
If you were to do just do go func(val interface{}) { ... }() without passing val, then the value of val will be whatever val is when the goroutines actually runs.
Another way to get the same effect is:
for val := range values {
val := val
go func() {
fmt.Println(val)
}()
}
The strange-looking val := val creates a new variable in each iteration, which is then accessed by the goroutine.
