[Python-Dev] Thread safety of deques

[Moore, Paul]

The documentation for the collections.deque type states that "Deques
support thread-safe, memory efficient appends and pops from either
side of the deque". I'm not clear what the implication of saying that
these operations are "thread-safe" is.

To contrast, list.append() does not claim thread safety. Should I
therefore conclude that to append an item in a thread-safe manner to a
list requires a mutex, but not for a deque?

Overall, the documentation does not tend to state what operations
are "atomic" in thread-safety terms. Continuing that trend, it may
be better *not* to make any statement about deques. If we do, then
not saying anything about other types seems to imply that they are
not thread-safe. Which may well be true, but if so should probably
be explicit, once we start making thread safety claims of other data
structures.

This way to the slippery slope... :-)

Paul.


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