Python - wait on a condition without high cpu usage

Question

In this case, say I wanted to wait on a condition to happen, that may happen at any random time.

 while True:
    if condition:
        #Do Whatever
    else         


        

Answer 1

This is not really a Python problem. Optimally, you want to put your process to sleep and wait for some sort of signal that the action has occured, which will use no CPU while waiting. So it's not so much a case of writing Python code but figuring out what mechanism is used to make condition true and thus wait on that.

If the condition is a simple flag set by another thread in your program rather than an external resource, you need to go back and learn from scratch how threading works.

Only if the thing that you're waiting for does not provide any sort of push notification that you can wait on should you consider polling it in a loop. A sleep will help reduce the CPU load but not eliminate it and it will also increase the response latency as the sleep has to complete before you can commence processing.

As for waiting on events, an event-driven paradigm might be what you want unless your program is utterly trivial. Python has the Twisted framework for this.