pop & append

Gordon McMillan gmcm at hypernet.com
Mon Aug 30 18:26:12 CEST 1999


Robin Becker writes:

> Someone from the Zope list tells me that the list pop and append
> operations are thread safe. Is this the case? 

Yes, from the perspective of the thread doing the append / pop (*).

> How can one tell if
> particular bits of python code are 'atomic'?

If it happens in one op-code, (how's that for a non-answer :-)).

(*) The fact that the append / pop is thread safe doesn't mean that 
it won't screw up another thread which is iterating the list. Such 
iterations should always use a copy (list[:], which is also atomic), 
or protect the list with a Condition (and iterate as fast as 
possible).

- Gordon




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