Re: Timer scheduling and cancel-timer

[Paul Eggert <eggert@cs.ucla.edu>]

On 01/20/2013 07:58 AM, Tomohiro Matsuyama wrote:
>     (setq my-timer
>           (run-with-timer
>            nil 0.1
>            (lambda ()
>              (when my-timer
>                (cancel-timer my-timer)
>                (setq my-timer nil)
>                (sit-for 0.3)))))
> 
> After evaluating this code several times, you may see "zombie" timers
> in timer-list, though the code intends to keep at most one timer.

Hmm, isn't that due to a race in the above code?
A timer can fire when a timer action is running.

Do you get zombie timers with the following?
It should avoid the race.

    (setq my-timer
          (run-with-timer
           nil 0.1
           (lambda ()
             (let ((m my-timer))
               (when m
                 (cancel-timer m)
                 (setq my-timer nil)
                 (sit-for 0.3))))))