[Tutor] how to make a script do two things at once.
Kent Johnson
kent37 at tds.net
Mon Aug 22 04:45:33 CEST 2005
nephish wrote:
> Hey there,
> i have a simple question about getting a script to do
> two things at once.
> like this.
>
>
> for i in range(100):
> print i
> time.sleep(.2)
> if i == 15:
> os.system('python /home/me/ipupdate.py')
>
> print 'done'
>
> when i run this, it stops at 15 and runs the script called out in the
> os.system line. i know it is supposed to do that. But, how could i get a
> script to do this without stopping the count (or delaying it unill the
> script called exits)
One way to get a script to do two things 'at once' is to use threads. Threads are also a good way to introduce strange bugs into your program so you should do some reading about them. I can't find a good introduction - anyone else have a suggestion? Here is a brief one:
http://www.wellho.net/solutions/python-python-threads-a-first-example.html
Here are a couple of articles, not really introductory:
http://linuxgazette.net/107/pai.html
http://www.devshed.com/c/a/Python/Basic-Threading-in-Python/
Anyway here is something to get you started, this version of your program starts a new thread to do the os.system call, that way the main thread doesn't block.
import os, threading, time
def doSomething():
''' This function will be called from the second thread '''
os.system('''python -c "from time import sleep;sleep(2);print 'hello'"''')
for i in range(30):
print i
time.sleep(.2)
if i == 10:
print 'Starting thread'
threading.Thread(target=doSomething).start()
print 'done'
Kent
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