Dave Brueck dave at pythonapocrypha.com
Thu Sep 18 15:49:11 EDT 2003

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On Friday 19 September 2003 01:10 pm, Brian Alexander wrote:
> Hello;
>
> I am trying to protect some global data, which may, in the future, be
> accessed by threads. I'm not sure how to implement a locking mechanism
> in python. Here is the idea I'm trying to express:
>
> class resourceManager(object):
>   def __init__(self):
>    self.__resources = 100
>
>   def getResource(self):
>    BEGIN CRITICAL SECTION HERE
>    if self.__resources > 0:
>     self.__resources -= 1
>     * other related state information adjusted, too *
>    else:
>     emergencyCode()
>    END CRITICAL SECTION HERE
>
> How is this accomplished? Does anyone know of a simple example?

The basic idiom is to create a lock object somewhere:
lock = threading.Lock()
...

and then your critical section looks like:

lock.acquire()
try:
  dostuff
finally:
  lock.release()

-Dave

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