Interval race condition - AS3 bug??

Question

I have included the output and the two code segments that
trigger the output. I do not understand how this could happen.
Trace shows that clearInterval(19) occurs yet Wakeup seems to
trigger spontaneously still trying to clearInterval(19). This
occurs when user strums keypad triggering multiple calls to
KeyDownFunc. You can execute this code yourself by selecting
Lesson1 on page 1 of ItOnlyTakes1.org. It takes a few strumming
tries to trigger it but the following code demonstrates what is
happening within. Need help. (Interesting to note that 16 was never
cleared.)
Following code triggers the generation of a new display which
requires a user answer to be caught in KeyDownFunc. sleepID is a
global variable.
private function WakeUp():void {
clearInterval(sleepID);
trace("Wakeup calling: Cleared " + sleepID);
NewNumber();
Internal part of KeyDownFunc that calls WakeUp to trigger new
problem. The sleep interval is the time needed for the user to view
the correct answer was given BEFORE triggering a new WakeUP and
thus a new number
if (answer.length == subquanAnswer.length) {
if (answer == subquanAnswer && answerSign ==
subquanAnswerSign ) {
soundOutChannel = answerSound.play();
sleepID = setInterval(WakeUp, 1000);
trace("Call Wakeup: answer is " + answer + " " +
subquanAnswer + " New sleepID: " + sleepID);
gradeText.text=" CORRECT";
gradeText.setTextFormat(correctanswerformat);
} else {
gradeText.text=" INCORRECT";
gradeText.setTextFormat(incorrectanswerformat);
Output showing problem:
introListener calling
Call Wakeup: answer is 7 7 New sleepID: 2
Wakeup calling: Cleared 2
Call Wakeup: answer is 7 7 New sleepID: 4
Wakeup calling: Cleared 4
Call Wakeup: answer is 7 7 New sleepID: 6
Wakeup calling: Cleared 6
Call Wakeup: answer is 4 4 New sleepID: 8
Wakeup calling: Cleared 8
Call Wakeup: answer is 4 4 New sleepID: 10
Wakeup calling: Cleared 10
Call Wakeup: answer is 9 9 New sleepID: 12
Wakeup calling: Cleared 12
Call Wakeup: answer is 9 9 New sleepID: 14
Wakeup calling: Cleared 14
Call Wakeup: answer is 4 4 New sleepID: 16
Call Wakeup: answer is 4 4 New sleepID: 17
Wakeup calling: Cleared 17
Call Wakeup: answer is 6 6 New sleepID: 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19
Wakeup calling: Cleared 19

Answer 1

To all,
I understand the insistence to clear before setting, but I
have not figured out how to get clearing and setting into the same
function. I am currently using a flag to avoid the race condition
that my code, not AS3, has created. This is what I am rethinking.
My current flow is like this.
1) generate a NewNumber()
2) check keys until correct number entered using KeyEvent.
Then set an interval to wait until the student has had time to
consider the correctness of this answer and to play the audio
feedback.
3) Interval timeout triggers WakeUp which clears the interval
then generates a NewNumber.
Only problem was, kids kept entering keys AFTER they had
answered correctly which, before my using a flag, was triggering
new setIntervals and the problem above.
I do not see how I can have my KeyEvent handler clear the
interval or how I can have my WakeUp functions set the interval.
They are two distinct functions.
If I do not clear the interval in WakeUp a long delay in
answering will trigger another NewNumber.
If I set it in WakeUp then I don't give the student enough
time to answer.
If I do not set it in keydown then I don't know how to ensure
they have time to see and hear the feedback
I can't clear it in KeyDownFunc because the kid may not push
a key and allow WakeUP to create a NewNumber()
I hope my brain isn't frying.
I do appreciate the continued effort in helping me and help
on this forum has improved my coding almost as much as if I had
someone watching over my shoulder. LOL, that would be
instantaneous.