On Sunday, 29 January 2017 01:42:08 UTC+11, T L wrote:
>
>
>
> On Saturday, January 28, 2017 at 10:33:08 PM UTC+8, Dave Cheney wrote:
>>
>>
>>
>> On Sunday, 29 January 2017 01:25:20 UTC+11, 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.
>>>
>>
>> Yes. The only reasonable way to interpret the operation of SetFinalizer
>> is to assume it does not thing and program accordingly.
>>
>> To repeat, you cannot base the correct operation of your program on a
>> finaliser running before your program exits.
>>
>
> I know, I just want to make sure some fanalizers will get executed for a
> long running program.
>
Finalisers are not guaranteed to run, no matter how long the program runs
for, no matter how important they are.
> But it looks the current implementation of SetFinalizer can't make any
> guarantee at all.
>
Correct. Finalisers are not guaranteed to run. You should not base the
correct operation of your program on a finaliser running before your
program exits.
>
>
>>
>>> 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)
>>> }
>>>
>>>
>>>>
>>>>
>>>> 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?
>>>>>
>>>>
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
