Thanks for the explanation!
I ended up ignoring cleanup checks if test failed (=> runtime.Goexit() is
called)
IMHO it's somewhat counter-intuitive that after calling runtime.Goexit()
something is still held...
On Friday, April 4, 2025 at 7:18:32 AM UTC+3 Robert Engels wrote:
> And as Sean pointed out, the reason it is never run is that the object
> being cleaned up is still referenced (I didn’t verify this)
>
> On Apr 3, 2025, at 5:28 PM, Yaroslav Brustinov <y.bru...@gmail.com> wrote:
>
>
>
> I was sure the doc means the case when a program exits *too quickly,*
> before cleanup has a chance to run, or am I wrong?
> Otherwise, why need to specify "not guaranteed to run before program
> exit."? It obviously can't run after program exits :)
>
> In the code example above, I can wait indefinitely for cleanup to run, it
> will not trigger:
>
> for range 20 { // <-- can increase this arbitrary
> runtime.GC()
> if releaseFlag.Load() {
> fmt.Println("released, cond:", goexit)
> return
> }
> time.Sleep(10 * time.Millisecond)
> }
>
>
> On Thursday, April 3, 2025 at 8:50:24 PM UTC+3 robert engels wrote:
>
>> It states this in the API docs:
>>
>> "The cleanup(arg) call is not always guaranteed to run; in particular it
>> is not guaranteed to run before program exit."
>>
>> On Apr 3, 2025, at 10:23 AM, Yaroslav Brustinov <y.bru...@gmail.com>
>> wrote:
>>
>> Hello, experts.
>>
>> Given following code as example:
>>
>> package main
>>
>> import (
>> "fmt"
>> "io"
>> "runtime"
>> "sync/atomic"
>> "time"
>> )
>>
>> type S struct {
>> foo int
>> }
>>
>> var released1 atomic.Bool
>> var released2 atomic.Bool
>>
>> func releaseCb(releaseFlag *atomic.Bool) {
>> fmt.Println("release CB")
>> releaseFlag.Store(true)
>> }
>>
>> func deferredCheckRelease(goexit bool, releaseFlag *atomic.Bool) {
>> for range 20 {
>> runtime.GC()
>> if releaseFlag.Load() {
>> fmt.Println("released, cond:", goexit)
>> return
>> }
>> time.Sleep(10 * time.Millisecond)
>> }
>> fmt.Println("not released, cond:", goexit)
>> }
>>
>> func f(goexit bool, releaseFlag *atomic.Bool) {
>> defer deferredCheckRelease(goexit, releaseFlag)
>> s := &S{1}
>> runtime.AddCleanup(s, releaseCb, releaseFlag)
>> if goexit {
>> // releaseFlag will not be set
>> runtime.Goexit()
>> }
>> // releaseFlag will be set
>> fmt.Fprint(io.Discard, s)
>> }
>>
>> func main() {
>> go f(true, &released1)
>> go f(false, &released2)
>> time.Sleep(time.Second)
>> }
>>
>> As comment inside mentions, release flag is not set if runtime.Goexit()
>> executed.
>>
>> Maybe it's because runtime.AddCleanup is not "guaranteed" to run?
>> In such case would be great to clarify (in docs?) in which cases it might
>> not run.
>> People might rely on the callback...
>>
>>
>>
>>
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>>
>>
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