threading - race condition?

[Gabriel Genellina]

En Fri, 09 May 2008 01:30:32 -0300, skunkwerk <skunkwerk at gmail.com>  
escribió:

> On May 8, 4:54 pm, castiro... at gmail.com wrote:
>> On May 8, 5:45 pm, skunkwerk <skunkw... at gmail.com> wrote:
>>
>>
>>
>> > i'm getting the wrong output for the 'title' attributes for this
>> > data.  the queue holds a data structure (item name, position, and list
>> > to store results in).  each thread takes in an item name and queries a
>> > database for various attributes.  from the debug statements the item
>> > names are being retrieved correctly, but the attributes returned are
>> > those of other items in the queue - not its own item.  however, the
>> > model variable is not a global variable... so i'm not sure what's
>> > wrong.
>>
>> > i've declared a bunch of workerthreads(100) and a queue into which
>> > new requests are inserted, like so:
>>
>> > class SimpleDBThread ( threading.Thread ):
>> >    def __init__ ( self, queue ):
>> >                 self.__queue = queue
>> >                 threading.Thread.__init__ ( self )
>> >    def run ( self ):
>> >                 while 1:
>> >                         item = self.__queue.get()
>> >                         if item!=None:
>> >                                 model = domain.get_item(item[0])
>> >                                 logger.debug('sdbthread  
>> item:'+item[0])
>> >                                 title = model['title']
>> >                                 scraped = model['scraped']
>> >                                 logger.debug("sdbthread title:"+title)
>>
>> > any suggestions?
>>
>> If man arises as a tool-carrier, we will carry tools, not people.
>> Don't use Python to make people; make money, and not too much.  Pick a
>> wage and you might get somewhere.
>
> excuse me?

(Please forgive our local pet)

is "item" a list? Perhaps the *same* list as other requests? Be careful  
when you put mutable objects in a queue.
And what about domain.get_item? is it a thread safe operation?
You said the model is not a global - but is it a *different* object for  
each request?

-- 
Gabriel Genellina