scheduler or infinite loop

Wed Sep 29 09:04:23 EDT 2010

harryos wrote:
> hi
> I am trying to write a program to read data from a site url.
> The program must read the data from site every 5 minutes.
>> def get_data_from_site(pageurlstr):
> h=urllib.urlopen(pageurlstr)
> data=h.read()
> process_data(data)
>> At first, I thought of using the sched module ,but then it doesn't
> look right adding so many scheduler.enter() statements.The program is
> supposed to execute the above function every
> 5 minutes until the application is shut down by the user.
>> I created an infinite loop
> while True:
> print time.asctime()
> get_data_from_site('http://somesite.com/')
> time.sleep(300)
>> Is there a better way to do this?Any suggestions ,pointers most
> welcome
> thanks
> harry

Here is a technique that allows the loop to run in the background, in its 
own thread, leaving the main program to do other processing -
import threading
class DataGetter(threading.Thread):
 def __init__(self):
 threading.Thread.__init__(self)
 self.event = threading.Event()
 def run(self):
 event = self.event # make local
 while not event.is_set():
 print time.asctime()
 # either call the function from here,
 # or put the body of the function here
 get_data_from_site('http://somesite.com/')
 event.wait(300)
 def stop(self):
 self.event.set()
In the startup of the main program, insert the following -
 data_getter = DataGetter()
 data_getter.start()
At the end of the program, terminate the loop like this -
 data_getter.stop()
HTH
Frank Millman