Emanuele D'Arrigo schrieb:
Hi everybody,
Assuming a snippet such as:
threadLocalData = threading.local()
threadLocalData.myDictionary = self.myDictionary
is it correct to say that threadLocalData.myDictionary is NOT a thread-
local -copy- of self.myDictionary but it's actually pointing to the
same object?
Yes, it's pointing to the same object, and it thus makes the whole
purpose of threadlocal moot. Use a global.
> If that's the case, and assuming I want to iterate over the dictionary
> without it changing under my nose while I'm in the loop, would it be
> better to encase the whole loop in lock-protected section or would it
> be better to make a copy of the dictionary first and then iterate over
> that one? Given that in this particular thread I do not want to modify
> the dictionary, conceptually a copy would work. But would making
> thread-local copy be just as slow as making the whole loop thread
> safe?
As MRAB pointed out - it depends. My gut feeling on this is that the
copy-approach is fastest. Or even faster, if you can cope with keys
getting lost while processing them:
for key in self.myDictionary.keys():
try:
value = self.myDictionary[key]
except KeyError:
pass
Diez
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