Safely add a key to a dict only if it does not already exist?
steve+comp.lang.python at pearwood.info
Sat Jan 19 05:07:13 CET 2013
I wish to add a key to a dict only if it doesn't already exist, but do it
in a thread-safe manner.
The naive code is:
if key not in dict:
dict[key] = value
but of course there is a race condition there: it is possible that
another thread may have added the same key between the check and the
How can I add a key in a thread-safe manner?
Any solutions must work with built-in dicts, I cannot use a custom dict
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