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Hallo!


I have a problem with this little script written in Python:


import sys, os, time
texts = ['this is text1', 'this is text 2']
for current_text in env_sources[0:]:
pid = os.fork()
if pid == 0:
time.sleep(2)
print current_text
break

As you is create some child processes depending on the number of vars
in ?texts?. My problem is: How can I run some code after all child
processes have been finished? (The code should be run only in the
parent process.)

I tried:

import sys, os, time
texts = ['this is text1', 'this is text 2']
for current_text in texts[0:]:
pid = os.fork()
if pid == 0:
time.sleep(2)
print current_text
break
os.waitpid(-1, 0)
print 'this is the end'

But this didn't work, 'this is the end' will be showed several times.

Can you help me?

Tanks.


Markus

First, you'll want to exit from each forked copy, or else it will reach
the code-after-the-for-loop:
import sys, os, time
texts = ['this is text1', 'this is text 2']
for current_text in texts[0:]:
pid = os.fork()
if pid == 0:
time.sleep(2)
print current_text
raise SystemExit

Next, you'll want to wait for each process you started:
for current_text in texts:
os.waitpid(-1, 0)
print 'this is the end'


$ python /tmp/franz.py
this is text1
this is text 2
this is the end

Jeff

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On Sat, 25 Dec 2004 08:20:24 -0600
Jeff Epler <> wrote:

> Next, you'll want to wait for each process you started:
> for current_text in texts:
> os.waitpid(-1, 0)
> print 'this is the end'

This can eventually die with exception. The proper way is:

try:
while True:
os.waitpid(-1, 0)
except OSError, exc:
if exc.errno!=errno.ECHILD:
raise

--
Denis S. Otkidach
http://www.python.ru/ [ru]