How to Implement a Recurring Function with 'threading.Timer' Without the 'RuntimeError: threads can only be started once' Issue?

Implementing a Recurring Function with 'threading.Timer'

Creating a function that runs repeatedly every 'n' seconds is a common requirement in programming. However, using 'threading.Timer' for this purpose can present challenges.

One approach involves starting a timer thread multiple times, as shown in the pseudo code below:

t=threading.timer(0.5,function)
while True:
    t.cancel()
    t.start()

However, this may result in a 'RuntimeError: threads can only be started once' error because 'threading.Timer' objects can only be started once. To address this, we can create a custom thread class that handles the repeated execution and cancellation of the timer:

class MyThread(Thread):
    def __init__(self, event):
        Thread.__init__(self)
        self.stopped = event

    def run(self):
        while not self.stopped.wait(0.5):
            print("my thread")
            # call a function

In the main code, we can create an event to control the timer thread:

stopFlag = Event()
thread = MyThread(stopFlag)
thread.start()
# this will stop the timer
stopFlag.set()

By using this approach, we can start and stop the recurring function as needed, without encountering the 'RuntimeError' issue.

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