init() functions should not spawn goroutines.
See also Avoid init().
If a package has need of a background goroutine,
it must expose an object that is responsible for managing a goroutine's
lifetime.
The object must provide a method (Close, Stop, Shutdown, etc)
that signals the background goroutine to stop, and waits for it to exit.
| Bad | Good |
|---|---|
func init() {
go doWork()
}
func doWork() {
for {
// ...
}
} |
type Worker struct{ /* ... */ }
func NewWorker(...) *Worker {
w := &Worker{
stop: make(chan struct{}),
done: make(chan struct{}),
// ...
}
go w.doWork()
}
func (w *Worker) doWork() {
defer close(w.done)
for {
// ...
case <-w.stop:
return
}
}
// Shutdown tells the worker to stop
// and waits until it has finished.
func (w *Worker) Shutdown() {
close(w.stop)
<-w.done
} |
|
Spawns a background goroutine unconditionally when the user exports this package. The user has no control over the goroutine or a means of stopping it. |
Spawns the worker only if the user requests it. Provides a means of shutting down the worker so that the user can free up resources used by the worker. Note that you should use |