func main() {
ctx, cancel := context.WithTimeout(context.Background(), 5 * time.Second)
defer cancel()
go f1(ctx)
for i := 0; i < 10; i++ {
select {
case <-ctx.Done():
fmt.Println("timed out")
default:
fmt.Println("main sleep for 1 second")
time.Sleep(time.Second)
}
}
time.Sleep(30 * time.Second)
fmt.Println("main slept for 30 seconds")
}
func f1(ctx context.Context) {
go f2()
time.Sleep(10 * time.Second)
fmt.Println("f1 slept for 10 seconds")
}
func f2() {
time.Sleep(20 * time.Second)
fmt.Println("f2 slept for 20 seconds")
}
zzh@ZZHPC:/zdata/Github/ztest$ go run main.go main sleep for 1 second main sleep for 1 second main sleep for 1 second main sleep for 1 second main sleep for 1 second main sleep for 1 second timed out timed out timed out timed out f1 slept for 10 seconds f2 slept for 20 seconds main slept for 30 seconds
From the output, we can see that context timing out cannot stop goroutines from executing.
context.Context can only relay the message that timeout or cancellation happened. It does not have the power to actually stop any goroutines (for details, see cancel a blocking operation in Go). The goroutine itself is responsible for checking the timeout and cancellation, and abort early.
func main() {
ctx, cancel := context.WithTimeout(context.Background(), 5 * time.Second)
defer cancel()
go f1(ctx)
for i := 0; i < 10; i++ {
select {
case <-ctx.Done():
fmt.Println("timed out")
default:
fmt.Println("main sleep for 1 second")
time.Sleep(time.Second)
}
}
time.Sleep(30 * time.Second)
fmt.Println("main slept for 30 seconds")
}
func f1(ctx context.Context) {
go f2()
select {
case <-ctx.Done():
fmt.Println(ctx.Err())
case <-time.After(10 * time.Second):
fmt.Println("f1 slept for 10 seconds")
}
}
func f2() {
time.Sleep(20 * time.Second)
fmt.Println("f2 slept for 20 seconds")
}
zzh@ZZHPC:/zdata/Github/ztest$ go run main.go main sleep for 1 second main sleep for 1 second main sleep for 1 second main sleep for 1 second main sleep for 1 second context deadline exceeded timed out timed out timed out timed out timed out f2 slept for 20 seconds main slept for 30 seconds
标签：timed,second,sleep,context,Go,main,out From： https://www.cnblogs.com/zhangzhihui/p/18029200