Timer module?

[Lee, Rick]

The sleep() function in the time module blocks.

I wonder if there is already any timer module out there that allows me
to:

- set a timer without blocking the current thread
- cancel the timer
- maybe also, able to tell it to recur at a given interval for so many
times; and able to change that
- create thousands of timers with a performance penalty that grows
slower than linearly with the number of timers; preferably a performance
cost that is small and almost constant

Thanks.

- Rick Lee