littlesweetmelon@gmail.com wrote:
Q1: How to determine a function is 'blocking action' or not? Any function needs CPU times. Indeed, a computational-intensive function is blocking action. But how small/fast function can be classified as non-blocking?
glyph@divmod.com wrote:
You've basically answered your own question here. A "blocking action" is one where your users will not want to wait for it :).
A value typically used as a reference point, on a human time scale, is a hundredth of a second, that is, 0.01s, that is, 10ms. If that's the maximum processing time of each event, you may expect a rate of at least 100 events per second, with a good overall event flow in the system, depending on the system load.
Twist requires all user functions to be non-blocked. If reactor calls a blocking function, what will happen? In my mind, reactor maintains a command queue internally (just like windows message queue). The blocking function only postpones the execution of other queued functions, but it does not break the logic of the program. Is that right?
Yes, that's right. The processing of subsequent events will be delayed, but the program will still run correctly, *if* its correctness does not depend on the timing of event processing. -- Nicola Larosa - http://www.tekNico.net/ E-mail can be saved by your ISP or by the IT department in your corporation. Gmail, for example, saves everything, even if you delete it. -- Bruce Schneier, November 2006