I have this code in one of my apps:
townCache = {}
def getTown(id):
if not id in townCache:
townCache[id] = TownModel.get_by_id(id)
return townCache[id]
Is this thread safe? I think it is, because the worst that happens is the
assignment happens redundantly with the same data.
Random other question: Why don't I have to say "global townCache" at the top of
that function?
On Jun 29, 2011, at 7:43 AM, Joshua Smith wrote:
> I would assume they are the same as the basic principles of thread safety in
> any language:
>
> - Don't rely on global state, because multiple of your functions might be
> running simultaneously
>
> This usually isn't very hard to achieve - just pass parameters instead of
> modifying globals. The places where it can get tricky are where you really
> *want* to use global state, such as for an in-memory cache. Usually the
> language provides some primitives to ensure that only one thread at a time is
> updating the cache. It appears that python gives you thread-safety for a lot
> of cases:
>
> http://effbot.org/zone/thread-synchronization.htm
>
> On Jun 29, 2011, at 1:20 AM, Greg wrote:
>
>> Hi -
>>
>> Could anyone familiar with threads explain the basic principals of
>> python thread-safety?
>>
>> Cheers!
>> Greg.
>>
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