dictionaries and threads

[Gary Robinson]

Hi,

I know the Global Interpreter Lock ensures that  only one python thread 
has access to the interpreter at a time, which prevents a lot of 
situations where one thread might step on another's toes.

But I'd like to ask about a specific situation just to be sure  I 
understand things relative to some code I'm writing.

I've got a dictionary which is accessed by several threads at the same 
time (that is, to the extent that the GIL allows). The thing is, 
however, no two threads will ever be accessing the same dictionary 
items at the same time. In fact the thread's ID from thread.get_ident() 
is the key to the dictionary; a thread only modifies items 
corresponding to its own thread ID. A thread will be adding an item 
with its ID when it's created, and deleting it before it exits, and 
modifying the item's value in the meantime.

As far as I can tell, if the Python bytecodes that cause dictionary 
modifications are atomic, then there should be no problem. But I don't 
know that they  are because I haven't looked at the bytecodes.

Any feedback on this would be appreciated. For various reasons, we're 
still using Python 2.3 for the time being.

Gary

-- 

Gary Robinson
CTO
Emergent Music, LLC
grobinson at goombah.com
207-942-3463
Company: http://www.goombah.com
Blog:    http://www.garyrobinson.net