I can't get RLock to work (warning, the following code is pretty long)

grocery_stocker cdalten at gmail.com
Fri Apr 10 17:15:29 CEST 2009


On Apr 10, 6:48 am, Peter Otten <__pete... at web.de> wrote:
> grocery_stocker wrote:
> > When I run the following...
>
> > #!/usr/bin/python
>
> > import time
> > import thread
> > import threading
>
> > def get_first_part(string, lock, sleeptime, *args):
> >         global counter
> >         lock.acquire()
> >         try:
> >                 counter = counter + 1
> >                 data = counter
> >                 print "%s value is %d" % (string, counter)
> >                 time.sleep(sleeptime)
> >         finally:
> >                 lock.release()
> >         return data
> > def get_both_parts(string, lock, sleeptime, *args):
> >         global first, second
> >         lock.acquire()
> >         try:
> >                 first = get_first_part()
> >                 second = get_second_part()
> >                 print "%s values are %d and %d" % (string, first,
> > second)
> >                 time.sleep(sleeptime)
> >         finally:
> >                 lock.release()
> >                 return first, second
> > How come RLock isn't working in this example?
>
> When get_both_parts() acquires the lock it invokes get_first_part() which
> tries to acquire the lock. This fails because get_both_parts() does not
> release the lock until after get_first_part() has finished...
>
> Peter


i thought a Rlock() (vs a Lock()) was suspposed to get around this
kind of a problem.



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