Correct way to do timer function in Python

Question

I have a GUI application that needs to do something simple in the background (update a wx python progress bar, but that doesn't really matter). I see that there is a threading.timer class.. but there seems to be no way to make it repeat. So if I use the timer, I end up having to make a new thread on every single execution... like :

import threading
import time

def DoTheDew():
    print "I did it"
    t = threading.Timer(1, function=DoTheDew)
    t.daemon = True
    t.start()    

if __name__ == '__main__':
    t = threading.Timer(1, function=DoTheDew)
    t.daemon = True
    t.start()
    time.sleep(10)

This seems like I am making a bunch of threads that do 1 silly thing and die.. why not write it as :

import threading
import time

def DoTheDew():
    while True:
        print "I did it"
        time.sleep(1)


if __name__ == '__main__':
    t = threading.Thread(target=DoTheDew)
    t.daemon = True
    t.start()
    time.sleep(10)

Am I missing some way to make a timer keep doing something? Either of these options seems silly... I am looking for a timer more like a java.util.Timer that can schedule the thread to happen every second... If there isn't a way in Python, which of my above methods is better and why?

What's wrong with second variant? It is a standard way to accomplish your task in Python — nkrkv
– nkrkv, Commented May 25, 2010 at 16:36
This is much more about wxPython than Python itself. You downplayed the significance of what you're trying to do (update a progress bar) but you shouldn't. — FogleBird
– FogleBird, Commented May 25, 2010 at 16:46
I just thought as a general programming thing.. there is stuff I may want to do every X seconds. If the second way is the normal way, cool. threading.Timer seems pretty darn weak though. — bwawok
– bwawok, Commented May 25, 2010 at 16:51

FogleBird · Accepted Answer · 2010-05-25 16:50:56Z

3

A pattern more like this is probably what you should be doing, but it's hard to say because you didn't provide many details.

def do_background_work(self):
    # do work on a background thread, posting updates to the
    # GUI thread with CallAfter
    while True:
        # do stuff
        wx.CallAfter(self.update_progress, percent_complete)

def update_progress(self, percent_complete):
    # update the progress bar from the GUI thread
    self.gauge.SetValue(percent_complete)

def on_start_button(self, event):
    # start doing background work when the user hits a button
    thread = threading.Thread(target=self.do_background_work)
    thread.setDaemon(True)
    thread.start()

answered May 25, 2010 at 16:50

FogleBird

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Andrew E. Falcon · Accepted Answer · 2010-05-25 16:37:53Z

2

wxwindows has its own timer. It supports one shot, and reoccurring events.

answered May 25, 2010 at 16:37

Andrew E. Falcon

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2 Comments

bwawok Over a year ago

Ah good call. Solves my wx problem, but not my overall python one.

Andrew E. Falcon Over a year ago

If the problem is you need to run it in a different thread, then there is nothing wrong with the loop around sleep(). If the task is short, I would try to avoid the thread so I wouldn't have to worry about locking resources.

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