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How does the bsddb wrapper achieve thread safety?
I know very little about the wrapper or the underlying bsddb
libraries. I found the following comment in the C API docs:
http://www.sleepycat.com/docs/ref/program/mt.html#2
> When using the non-cursor Berkeley DB calls to retrieve 
> key/data items (for example, DB->get), the memory to which
the 
> pointer stored into the Dbt refers is valid only until the
next call 
> using the DB handle returned by DB->open. This includes any 
> use of the returned DB handle, including by another thread 
> within the process.
This suggests that a call to a self->db->get() must process
its results (copy them into Python-owned memory) before any
other operation on the same db object can proceed. Is that
right?
The bsddb wrapper releases the GIL before calling the
low-level DB API functions and the acquires it after the
call returns. Is there some other lock that prevents
multiple simultaneous calls from stomping on each other?