On Saturday, January 28, 2017 at 10:25:20 PM UTC+8, T L wrote:
>
>
>
> On Saturday, January 28, 2017 at 9:33:51 PM UTC+8, C Banning wrote:
>>
>> From the doc: "The finalizer for obj is scheduled to run at some
>> arbitrary time after obj becomes unreachable. There is no guarantee that
>> finalizers will run before a program exits, so typically they are useful
>> only for releasing non-memory resources associated with an object during a
>> long-running program."
>>
>
>
> If this is true, then the SetFinalizer function would be much meaningless.
>
> BTW, it looks both finalizer will get executed if let the program sleep
> more than 10us at the beginning:
>
> package main
>
> import "time"
> import "runtime"
>
> func main() {
> time.Sleep(10 * time.Microsecond)
> // if sleep 10 Microsecond here, 2 and 1 will both be out
> // if sleep 1 Microsecond here, still only 2 will out
>
> t1 := new(int)
> t2 := new(int)
>
> runtime.SetFinalizer(t1, func(*int) {println(1)})
> runtime.SetFinalizer(t2, func(*int) {println(2)})
> runtime.GC()
> time.Sleep(time.Second * 20)
> }
>
>
BTW 2, it looks that the first finalizer set in a limited escaped time for
one-word data pointer will not get executed:
package main
import "time"
import "runtime"
type T1 [2]int
type T2 [2]int
// this program will output both 1 and 2,
// but if the length of T2 changes to 1, then 2 will not be output
func main() {
t1 := new(T1)
t2 := new(T2)
runtime.SetFinalizer(t1, func(*T1) {println(1)})
runtime.SetFinalizer(t2, func(*T2) {println(2)})
runtime.GC()
time.Sleep(time.Second * 1)
}
>
>>
>> On Saturday, January 28, 2017 at 6:17:37 AM UTC-7, T L wrote:
>>>
>>>
>>>
>>> package main
>>>
>>> import "time"
>>> import "runtime"
>>>
>>> type T1 struct{ i int }
>>> type T2 struct{ i int }
>>>
>>> func main() {
>>> t1 := new(T1)
>>> t2 := new(T2)
>>>
>>> runtime.SetFinalizer(t1, func(*T1) {println(1)})
>>> runtime.SetFinalizer(t2, func(*T2) {println(2)})
>>> runtime.GC()
>>> time.Sleep(time.Second * 2)
>>>
>>> // the program will output: 2
>>> // if I adjust the order of the declarations of t1 and t2,
>>> // the program will output: 1
>>> }
>>>
>>> Why the finalizer for the first declaration will not get called?
>>>
>>
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