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From Vadim Raskin <raskinva...@gmail.com>
Subject Re: [LONG] Discussing my implementation of Go actions
Date Sat, 10 Mar 2018 20:47:19 GMT
>> So, how can I check the process is actually terminated ?

Hi Michele,

what about using cmd.Wait() to check whether the process exited after you
started a go action? It will return a non-nil in case of error, otherwise
blocks forever waiting the process to finish. Waiting for a reasonable
amount of time to make sure that process doesn't exit and close the /init
call afterwards, would it cover the case you mentioned?

Just to make sure we talk about the same thing:

errorChan := chan string

cmd := exec.Command("userBinary")
cmd.Start()
// wait for failure to happen
go func(){
err := cmd.Wait()
if(err != nil){
errorChan <- "exited with failure"
}
else {
close(errorChan)
}
}()
// wait at most 10ms for an error to happen
go func(){
time.Sleep(10 * time.Millisecond)
errorChan <- "happy"
}
runResult <- errorChan
// further processing.

I haven't tested this code, it also needs to do some clean up of the Wait
go routine, but hopefully the logic is clear.

regards,
Vadim.

On Fri, Mar 9, 2018 at 3:18 PM Michele Sciabarra <michele@sciabarra.com>
wrote:

> > I would prefer it not be there, but can see the convenience of detecting
> > that an app has immediately crashed. If we can find another way to do
> > that via process inspection, that would be better in my view.
> >
> The problem can be summarised into this code:
>
>         // this command exits
>         cmd := exec.Command("true")
>         out, err := cmd.StdoutPipe()
>
>         err = cmd.Start()
>         fmt.Println(err)
>        // this is nil! no error!
>
>         // even worse! attempted to detect
>         err = cmd.Process.Signal(syscall.Signal(0))
>         // this is nil too! no error!
>         fmt.Println(err)
>
> So, how can I check the process is actually terminated ?
>

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